Tunable Diode Lasers (PDF) by nikeborome

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Diode Lasers

Turning Laser Diodes into
Diode Lasers
Laser diodes                                      Mode selection                                   Wavelength tuning of an ECDL
Laser diodes are well established in a            Requirements for advanced measurement            In an ECDL, a second resonator is formed
variety of consumer products, like laser          tasks include a narrow emission linewidth,       between the diode's back facet and the
pointers, barcode scanners, or CD/DVD/            large coherence length, precise wavelength       feedback elements. The grating filter,
Blu-ray drives. The success story of these        selection, and tuning or even stabilization      together with the semiconductor gain profile
light sources is driven by the fact that they     of the emission frequency. These superior        determines the new external lasing mode.
are compact, conveniently operated, cost          characteristics are achieved by introducing
effective, and highly efficient. However, the      an additional frequency-selective element        To control the wavelength of an ECDL, the
emission spectrum of bare laser diodes is         into the laser cavity. Precise temperature       angle of the grating is changed, shifting
broad, and the lasing wavelength is not well      and current control are a must.                  its spectral filter and at the same time
defined. The lasing modes are determined                                                            moving the external mode structure of the
by the two facets of the laser diode. The wide    TOPTICA offers two realizations of tunable       laser. A large mode-hop free tuning range
gain profile of the semiconductor causes           single-frequency diode lasers. Both make         results from accurate synchronization of
many modes to oscillate simultaneously,           use of grating structures to select and          the two effects. This can be realized by a
each with a different frequency.                  control the emission frequency. One is           properly selected pivot point for the grating
                                                  a grating stabilized external cavity diode       movement. Coarse wavelength alignment
Even diodes with a single longitudinal            laser (ECDL), which incorporates an optical      is often realized with a micrometer screw,
mode exhibit mode-hopping upon slightest          grating mounted in front of the laser diode.     automated tuning with a Piezo actuator.
variations of the chip temperature or driver      The other approach features laser diodes
current. The result is an imperfect, spectrally   with gratings built into the semiconductor       By adding a suitable grating, collimation
unstable output beam that does not meet           itself. Two versions of these diodes are used:   optics and control electronics, a simple laser
the demands of many scientific or industrial       distributed feedback (DFB) and distributed       diode can be transformed into a complete,
applications.                                     Bragg reflector (DBR) laser diodes (page 5).      tunable diode laser system.

4   www.toptica.com
                                                                                                                                                  Tunable Diode Lasers
Fabry-Perot and Anti-Reflection
Coated Laser Diodes
FP diodes — high power at a low cost               without external feedback. The AR coating     Important specifications for FP- or AR-
In TOPTICA's DL 100, an ECDL in Littrow            improves coarse and mode-hop free tuning      based ECDLs are the output power available
design, both Fabry-Perot (FP) diodes and           of an ECDL and allows for more stable         from the stabilized diode, the attainable
anti reflection coated (AR) diodes can              single-mode operation. TOPTICA's DL pro       wavelength range, and the mode-hop free

                                                                                                                                                  Frequency Converted Lasers
be used. FP diodes are mass-produced,              lasers therefore feature AR diodes.           tuning range. TOPTICA also sells laser
available at numerous wavelengths, and are                                                       diodes individually, and the diodes available
optimized for maximum output powers. In            AR diodes for best performance                from stock, together with their specifications,
addition, they are relatively cheap. With FP       The internal resonator of both FP and         are listed in our regularly updated stock list
diodes, the internal resonator of the diode        AR diodes can be synchronized with the        at www.laser-diodes.com.
functions like an etalon, attenuating certain      grating movement by changing the diode
external modes, and therefore participating        current simultaneously. This “feed forward”
in the selection of the external mode.             mechanism moves the internal mode
                                                   structure of the laser diode along with the     Laser diode with (red) and without
The effect of the internal resonator is less       external modes, permitting larger mode-         (blue) external grating feedback. The
pronounced when an AR coating is added             hop free tuning.                                left graph shows an FP diode, the right
on the output facet. AR diodes do not lase                                                         graph an AR diode.

DFB & DBR Diode Lasers

                                                                                                                                                  Single-Mode Diode Lasers
Laser diodes with internal grating                 ECDL or DFB?
Distributed Feedback (DFB) and Distributed         Whether to choose an
Bragg Reflector (DBR) laser diodes feature          external cavity diode laser or
a grating structure incorporated in the            a DFB/DBR laser depends
semiconductor chip. The grating restricts the      on the individual application.
laser emission to a single longitudinal mode       Contact the TOPTICA experts
and thus determines the lasing wavelength.         to find the best solution for
In a DFB laser, the grating is integrated into     your needs. DFB diodes do
the active region (“gain section”) of the diode.   not yet offer the wavelength
In a DBR laser, the grating (“Bragg section”)      range accessible by Littrow       Schematics of DFB and DBR laser diodes.
is separated from the gain region. An              ECDLs. Tunable, narrow-band
additional “phase section” serves to maintain      emission in the blue or red spectral range phase shifting interferometry, or the
mode-hop free resonance conditions during          is the realm of external-cavity systems. generation of tunable cw Terahertz
                                                                                                                                                  Ultrafast Fiber Lasers

a wavelength change.                               An ECDL is also the preferred choice for radiation. The mechanical design of a DFB
                                                   applications that require a broad coarse laser comprises no alignment-sensitive
Frequency tuning is accomplished by                tuning range, or an ultra-narrow linewidth optical components, making these lasers
thermally or electrically varying the grating      (1 MHz or below).                           particularly attractive for applications in
pitch. Thermal tuning offers extremely large                                                   rough industrial environments.
mode-hop free scans of hundreds of GHz.            The main advantage of a DFB laser is
Electric modulation, on the other hand, can        its extremely large continuous tuning
be employed for fast frequency modulation          range. Mode-hop free scans of several
over a smaller range (several tens of GHz @        nanometers are routinely attained. Typical
kHz to MHz modulation frequencies).                DFB laser applications are gas sensing,

                                                                                                                         www.toptica.com     5
      Tunable Diode Lasers

Littrow and Littman Configuration
Compact and robust Littrow setup                usually electronic noise, acoustic noise          Littman design usually employs AR coated
The most common types of ECDLs                  and vibrations that affect the cavity length.     diodes. FP diodes provide higher powers,
are the so-called Littrow and Littman           In practical operation, the compact and           encompass a broader wavelength range
configurations. In both cases, a grating is      more robust Littrow cavity often shows a          and are usually less expensive. However,
used to selectively reflect a small range of     narrower linewidth.                               TOPTICA also integrates AR coated diodes
the diode's emission spectrum back into                                                           when large tunability is required, and when
the laser chip. This optical feedback forces    Highest power from Littrow lasers                 power plays a secondary role.
the diodes into single-frequency operation.     The Littrow setup has further advantages.
In Littrow configuration, the first order         As the laser light reflects off the grating only   The mode-hop-free tuning range of Littrow
beam from the grating is directly reflected      once, losses into other diffraction orders        lasers can be greatly enhanced by adding
into the diode. In Littman configuration, by     do not occur. The output power of Littrow         a “feed forward” current modulation (see
contrast, the first diffraction order is first    lasers is thus considerably higher than that      page 5). The marginal angular change of
reflected from a mirror. It passes the grating   of comparable Littman setups. Moreover,           the output beam apparent with Littrow
a second time and is then sent back into        Littrow lasers can be operated with both          cavities can be effectively compensated for
the laser diode. In both setups, the main       standard Fabry-Perot (FP) diodes and anti-        by a beam steering mirror rotated in parallel
contribution to the technical linewidth are     reflection (AR) coated laser diodes, while the     with the grating.

                                                                                                            Mode selection in ECDLs. The
                                                                                                            back facet and the feedback
                                                                                                            elements form the external
                                                                                                            resonator. The oscillating mode
                                                                                                            is selected not only by these
                                                                                                            elements and the semiconductor
                                                                                                            gain, but also by the internal
                                                                                                            modes (etalon) of the diode.

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                                                                                                                                                 Tunable Diode Lasers
Frequency noise                                   Linewidth and drift                              Linewidth and coherence length
High stability and narrow linewidth are           Processes that are faster than the laser         Laser linewidth and coherence length are
often key requirements for scientific diode        frequency measurement itself, add to the         linked by an inverse proportionality. The
lasers. Theoretically, the linewidth of grating   laser's technical linewidth, while slower        numerical factor depends on the spectral
stabilized diode lasers is given by the           processes will cause a frequency drift           line shape. For a Gaussian spectral profile,

                                                                                                                                                 Frequency Converted Lasers
Schawlow-Townes formula and therefore             between successive measurements. As              the coherence length is 132 m / (linewidth
very narrow. In reality, however, a number        fast measurement techniques will not reveal      in MHz).
of processes and disturbances have an             slower drift effects on the linewidth, it is
effect on the laser frequency. Laser current      important to always note the time scale of
noise for example causes fluctuations of           the measurement when specifying linewidth
the refractive index within the laser diode       values.
itself, and changes the overall optical length
of the laser resonator. Acoustic noise and
vibrations have a direct influence on the
mechanical length of an external resonator,
while temperature and air pressure
fluctuations cause frequency drifts by                                                              Coherence coverage of more than
changing the refractive index of air.                                                              12 decades.

              Main causes for frequency variations and their respective time scales.

Linewidth measurement                             of 5 µs. Frequency fluctuations within this

                                                                                                                                                 Single-Mode Diode Lasers
TOPTICA uses different ways to measure            time contribute to the beat note, the width
laser linewidths. For fast measurements,          of which is approximately twice the laser‘s
a delayed self-heterodyne technique is            linewidth.
employed. The laser beam is split into two        Linewidth measurements on longer time
probe beams, one of which is frequency-           scales are accomplished by measuring the
shifted by an acousto-optical modulator           beat width of two identical lasers with a fast
and delayed utilizing a 1 km long fiber.           detector and an RF spectrum analyzer (sub
Subsequently, the beams are re-combined           Hz .. 100 MHz), by using a Fabry-Perot
on a fast photo detector, the output of which     interferometer (MHz .. GHz, see page 49),
is connected to an RF spectrum analyzer.          or by directly determining the coherence
The fiber line corresponds to a time delay         length with a Michelson interferometer.
                                                                                                                                                 Ultrafast Fiber Lasers

                                                                                                             Delayed self-heterodyne
                                                                                                             linewidth measurement.

                                                                                                                          www.toptica.com    7
pro Technology

Stability and Ease of Use
DL pro, TA pro, DL/TA-SHG/FHG pro

Modern physics experiments get more and        Our aim at TOPTICA is to develop lasers,          The next milestones are the pro versions of
more involved with an increasing number        that are the best of their class, more stable,    amplified (TA pro) and frequency converted
of instruments and especially laser sources    more reliable and at the same time easier         (DL/TA-SHG/FHG pro) tunable diode laser.
running simultaneously. Uncovering a           to use. The DL pro, a revolutionary new           Paying attention to every little detail these
faint signal never seen before from the        external cavity diode laser, introduced in        already established products have acquired
ever present noise background requires         2007, launched TOPTICA‘s pro series with          yet another edge. Last but not least, the pro
highest performance, a love of tiny detail,    great success. This laser was designed            technology concept at TOPTICA has also
dependability and trust in workmanship. At     with ultimate stability in mind – in particular   been incorporated into our line of ultrafast
TOPTICA, we come from laboratories like        stability against temperature changes and         lasers, emerging as the FemtoFiber pro.
our customers', and we understand what it      acoustic disturbances. The DL pro has             It completes the line of scientific “pro”
means to spend long nights relying on laser    quickly become the heart of TOPTICA's             laser products at TOPTICA. The pro series
technology for collecting data. Only the       diode laser activities, and we have been          ensures technological leadership for modern
best tools are good enough to contribute to    working hard to extend the design                 physics experiments for the years to come
such a competitive field. With this in mind,    principles also to other laser sources. The       and gives you the edge to put you ahead of
TOPTICA continues to follow a strategy to      DL pro‘s narrow linewidth and robustness          the crowd.
develop a second generation of its scientific   to temperature changes and vibrations are
instrumentation and make it broadly            unmatched by any other commercial diode           pro technology stands for:
available. We are now excited to introduce     laser. Together with our high end laboratory        Stability
the “pro” Technology.                          driver, control and locking electronics it has      Ease of use
                                               convinced many leaders in the field to trust         Thermal and acoustic ruggedness
                                               in pro technology.                                  Hands-off operation wherever possible
                                                                                                   Flexure joints wherever expedient

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                                                                                                                                               Tunable Diode Lasers
DL pro
Ultra-Stable Widely Tunable Littrow Laser

As the first laser of the pro series, the DL       Selected antireflection-coated (AR)

                                                                                                                                               Frequency Converted Lasers
pro has already demonstrated how much             diodes
even a well-established laser like the DL         In the DL pro only carefully selected AR
100 can be further improved.                      coated laser diodes are used. It is available
                                                  at four standard wavelengths, providing
Main advantages                                   most stable single-mode operation and
For the user the main advantages are              easy handling. Other wavelengths are
large mode-hop free tuning, alignment free        available on request.
operation, and highest acoustic and thermal
stability of any ECDL on the market. The          Motorization
result is most reliable and most convenient       The DL pro can also be equipped with a          DL pro — the ultimate Littrow
operation for high end laboratory work.           motor for wavelength selection. The user        diode laser.
                                                  can then choose the wavelength using
To achieve this ultimate performance              coarse or fine dials on the control box or
accompanied by ease of use, the DL pro            via computer control using an RS 232

mechanics possesses degrees of freedom            interface. The wavelength can be set to any
exactly where they are needed. Coarse and         value within the gain bandwidth of the diode
fine tuning have been skillfully separated:        with an accuracy of approximately 0.2 nm
Coarse tuning is performed by a well              by software commands. For further details
defined rotation of the grating, that precisely    on the motorized wavelength selection
selects any requested wavelength within           option MOT/DL pro, please contact your
the complete diode gain spectrum. Mode            local TOPTICA representative.
hop free tuning is realized by a system of
robust flexure joints that requires only tiny                                                      First class optomechanic (patent pending).
adjustments. It rotates the laser's grating
around the perfect “virtual” pivot point                                                          Key features
(international patent pending).
                                                                                                  · Ultra-stable mechanics
The compact and stable external cavity                                                            · Best Littrow design available

                                                                                                                                               Single-Mode Diode Lasers
resonator has its first mechanical resonance                                                       · Optimized virtual pivot point
above 4 kHz — one reason for its superior                                                         · 30 – 50 GHz mode-hop free tuning
acoustic stability. Special care has been                                                         · Convenient and simple coarse tuning
taken in choosing dimensions and materials                                                          up to 95 nm
to reduce frequency drifts due to variations of
the ambient temperature. Notwithstanding           Measured beat signal of two free running
its stability, the DL pro is easy to align. The    DL pro 780 averaged over 10 centered
experienced user can even exchange the             sweeps with a sweep time of 100 ms
laser diode himself.                               each. The resulting beat width is 308 kHz,
                                                   the linewidth approx. 150 kHz.
                                                                                                                                               Ultrafast Fiber Lasers


 DL pro Piezo transfer function. The               Laser frequency response to a 10 K air             Alignment free coarse tuning over
 first acoustic resonance is above                  temperature change (laser and electronics          tens of nm.
 4 kHz.                                            inside climate chamber).

                                                                                                                        www.toptica.com    9
     Tunable Diode Lasers

Standard Systems DL pro
Wavelengths and Specifications

                                  DL pro 780                 DL pro 850                 DL pro 940       DL pro 1040

 Wavelength range                765 – 795 nm               815 – 855 nm                915 – 985 nm      980 – 1075

 Max. output power                30 – 80 mW                 30 – 80 mW                 30 – 80 mW        20 – 50 mW

 Mode-hop free tuning             30 – 50 GHz                30 – 50 GHz                30 – 50 GHz       30 – 50 GHz

 Typical linewidth (5 µs)           100 kHz                    100 kHz                    100 kHz           100 kHz

 ASE (dB)                       < -35 .. -55 dB            < -35 .. -55 dB             < -35 .. -55 dB   < -35 .. -55 dB

 For further specifications and available options, please see pages 13 - 15.

       Normalized spectra of DL pro 780             Normalized spectra of DL pro 850
       at three different wavelengths.              at three different wavelengths.

       Normalized spectra of DL pro 940             Normalized spectra of DL pro 1040
       at three different wavelengths.              at three different wavelengths.

10   www.toptica.com
                                                                                                                                                   Tunable Diode Lasers
DL 100
External Cavity Diode Laser in Littrow Design

Principle of operation                              offer wider tuning, more stable single-mode

                                                                                                                                                   Frequency Converted Lasers
The excellent performance of the established        behaviour and narrowest linewidths.
DL 100 results from its Littrow type external-
cavity laser setup in a very rugged design.         The control and supply units are designed as
Micrometer screws allow for coarse manual           modular plug-ins which can be combined to
tuning, while precise mode-hop free scans           meet any application requirement. Further
are driven by a Piezo actuator. Lockable            modules like Scan Controls, Lock-In, PID
x/y/z adjustments together with metal               regulators and Pound-Drever-Hall detectors
flexures provide rigid and repeatable                complete the modular electronic setup.
control of both the laser beam collimation
and the feedback of the grating. The laser          Hands-on setup                                   DL 100 — one of the most common
resonator is thermally stabilized by means of       The DL 100 has evolved in research               lasers in research laboratories.
a Peltier cooler, connected to the DTC 110          laboratories and therefore offers multiple
Diode Temperature Control. Ultra low                features and the necessary versatility for
noise operation of the DL 100 is achieved           a changing environment. For instance, all
                                                                                                     Key features

by means of the Diode Current Control               important alignment parameters are easily
DCC 110. In addition, TOPTICA offers a              accessible from above and are adjustable         · Widest wavelength coverage
                                                                                                       375 .. 1670 nm
variety of electronic regulator modules to          by lockable micrometer screws. If an OEM
                                                                                                     · Highest power up to 300 mW
stabilize the laser frequency in demanding          application requires a fixed laser setup with
                                                                                                     · Coarse tuning up to 110 nm
scientific and industrial applications (for a full   limited user access, TOPTICA can also
description see pages 30 - 43).                     provide a “hands-off” version of their lasers.   · Mode-hop free tuning up to 30 GHz
                                                                                                     · Single-frequency operation
Modular design                                      Reasonably priced                                · Free running linewidth
The DL 100 diode laser head comprises a             The DL 100 Diode Laser Series with the             100 kHz .. 1 MHz (5 µs)
mounting base which serves as a heat sink,          Diode Control Unit DC 110, the Diode Current     · AR & FP diodes
a temperature sensor and Peltier cooler for         Control DCC 110 and the Diode Temperature        · Regularly updated diode stock list:
active temperature control, a laser base            Control DTC 110 is your complete step into
plate, a laser diode holder with a collimator       the “World of Diode Lasers”. Due to the          · Options: isolators, beam shaping, fiber
                                                                                                       coupling, high frequency modulation, ...
and a grating mount featuring a Piezo               strong emphasis on passive mechanical

                                                                                                                                                   Single-Mode Diode Lasers
actuator for precise tuning. The laser diode        stability, low thermal expansion and drifts,
itself can be easily exchanged by replacing         an excellent performance of the DL series
the diode holder without dismantling the            can be guaranteed at an affordable price.
setup. The DL 100 is available with AR and
FP diodes. FP diodes normally deliver higher
power at lower cost, while AR coated didoes
                                                                                                                                                   Ultrafast Fiber Lasers

  Linewidth of DL 100, determined with                DL 100 frequency sweep over four Rb
  a delayed self-heterodyne beat setup                absorption lines (red), utilizing feed
  (integration time 5 µs). The FWHM of                forward. FPI transmission peaks (blue,
  the beat signal is equal to two times the           FSR 1 GHz) are shown for reference.
  laser linewidth (450 kHz).

                                                                                                                          www.toptica.com     11
     Tunable Diode Lasers

Diode Lasers with Largest Mode-hop Free Tuning Range

                                           Wide wavelength range 760 .. 3000 nm              Frequency and linewidth control
                                           TOPTICA's DL DFB lasers offer wide                The high sensitivity of DFB diodes to
                                           tunability, narrow linewidth and high output      temperature variations requires precise
                                           power in a compact and very rugged setup.         control of the laser temperature. The
                                           Systems can be provided at any wavelength         DL DFB laser head incorporates TOPTICA's
                                           between 760 and 3000 nm. A large variety          patented ColdPack (see page 45): four
                                           of wavelengths is usually available from          thermoelectric elements stabilize the laser
                                           stock (including 780 nm, 785 nm, 795 nm,          temperature, or serve to heat and cool the
                                           852 nm, 895 nm, 935 nm and 1064 nm),              laser diode. TO-3 diode packages with built-
                                           but customized wavelengths can be realized        in TEC and thermistor, available at selected
 DL DFB laser heads with driving           even in low quantities and within short lead      DFB wavelengths, can also be mounted
 electronics (series DC 110).              times.                                            into the DL DFB laser head. To fully exploit
                                                                                             the attractive properties of DFB diodes, the
                                           The absence of any alignment-sensitive            laser system is equipped with TOPTICA's
                                           opto-mechanical components ensures high           low noise driver electronics SYS DC 110
 Key features                              long-term stability and reliability. The DL DFB   (see pages 32 - 39). Under laboratory
 · Every wavelength between 760 nm and     therefore opens new possibilities for projects    conditions, a frequency stability of 20 MHz
   3000 nm available                       that require automated operation, or even         (RMS) has been demonstrated over a 10-
 · High output power up to 150 mW          for airborne experiments.                         hour measurement period, without any
 · Mode-hop free tuning up to 1400 GHz                                                       additional frequency stabilization.
   (4 nm)                                  Frequency tuning of TOPTICA's DL DFB              The short-term laser linewidth is in the
 · Single-frequency operation, linewidth   lasers is accomplished by changing either         range of 500 kHz to 4 MHz (integration time
   typ. 0.5 .. 4 MHz (5 µs)                the chip temperature (frequency change            5 µs), depending on the diode wavelength.
 · Reliable operation even in harsh        ca. 25 GHz/K) or the operating current            TOPTICA can provide means to narrow the
   environments (no alignment-sensitive
   optomechanics)                          (frequency change 1-5 GHz/mA). Thermal            linewidth to well below 100 kHz. Please
 · Optional: high-frequency modulation,    tuning achieves extremely large mode-hop          inquire about a customized solution.
   optical isolation, fiber coupling       free scan ranges, electric tuning is favorable
 · Regularly updated diode stock list:     for rapid modulation and frequency                Application examples of DL DFB lasers
   www.laser-diodes.com                    stabilization tasks.                              include alkaline spectroscopy (K, Rb,
                                                                                             Cs), gas sensing (e.g. O2, H2O, methane),
                                                                                             holography, phase-shifting interferometry,
                                                                                             and the generation of tunable cw-Terahertz
                                                                                             (THz) radiation.

                                                     Thermal frequency tuning of                    Absorption spectrum of water
                                                     a DL DFB. Linearized scans                     vapor, recorded with a thermally
                                                     can be accomplished with                       tuned DL DFB at 935 nm.
                                                     TOPTICA's iScanTM technology
                                                     (see pages 42 - 43).

12   www.toptica.com
                                                                                                                                            Tunable Diode Lasers
Options DL Series

                                                                                                                                            Frequency Converted Lasers
Laser                                                 DL 100                          DL pro                         DL DFB
SP/DL 100                                            Included                        Included                      Not needed

DL-Mod                                               Optional                        Included                        Optional

Isolator 30 dB                                       Optional*                       Optional*                      Optional*

Isolator 60 dB                                       Optional*                       Optional*                      Optional*

APP J expanding                                      Optional*                       Optional*                      Optional*

APP compact                                          Optional*                       Optional*                      Optional*

FiberDock                                            Optional                        Optional                        Optional

*Not for all wavelengths and/or not in combination with all other options.

Beam angle compensation mirror: SP/DL 100
                             In TOPTICA's Littrow-type ECDL, the beam angle compensation mirror is mounted parallel to the gra-
                             ting to eliminate a change of the output beam angle when tuning the laser. It is included in the DL 100
                             and DL pro, and not needed for the DL DFB.

High frequency modulation PCB: DL-Mod
                             The PCB includes a FET and a Bias-T.
                             The FET is DC coupled with an electrical bandwidth (-3 dB) of 20 MHz. The Bias-T is AC-coupled with
                             an electrical bandwidth of > 300 MHz. The optical modulation bandwidths are generally lower and
                             depend on the properties of the diode.

Single-stage isolator: Isolator 30 dB

                                                                                                                                            Single-Mode Diode Lasers
                             Isolators are used to protect the laser diode from back reflections. This not only prevents damage to
                             the diode but also ensures untroubled single-mode operation and tuning. Fiber coupling with angle
                             polished fibers (both ends) requires at least a single stage isolator. See also page 47.

Double-stage isolator: Isolator 60 dB
                             Double stage isolators are needed if reflections from the experiment into the laser are expected. Fiber
                             coupling with non-angle polished fibers also requires a double stage isolator. See also page 47.

Adjustable anamorphic prism pair: APP J
                             TOPTICA's patented adjustable anamorphic prism pairs are used to expand or compress a laser beam
                             in one direction, by a factor between 2 and 5. The main application is to render an elliptical diode laser
                             beam circular. See also page 46.
                                                                                                                                            Ultrafast Fiber Lasers

Compact prism pair for beam compression: APP compact
                             The compact prism pair is used for beam compression only. The compressed circular beam is small
                             enough for using inexpensive small aperture isolators, and the fiber coupling efficiency is enhanced by
                             approximately 10 %. The compression ratio is set at the factory.

Fiber coupler: FiberDockTM
                             TOPTICA's patented fiber coupler provides highest single-mode fiber coupling efficiencies, easy align-
                             ment and at the same time highest stability. TOPTICA additionally offers a wide range of single-mode
                             and polarization maintaining fibers, including fiber-optic beam splitters. Optical isolation is mandatory for
                             fiber-coupled diode laser systems. See also page 48.

                                                                                                                   www.toptica.com     13
     Tunable Diode Lasers

Configurations DL Series
Diode Lasers DL 100, DL pro, DL DFB

 Configurations                                                                Available wavelenths
 Configuration I                         Consists of                           DL 100              DL pro           DL DFB
                                        •    DL 100, DL pro, DL DFB           Given by avail-     See page 10      660
                                        +    Modulation PCB DL-Mod            able laser diodes                    760 – 3000 nm
                                             (optional)                       (www. laser-

 Configuration II                        Consists of
                                        •    DL 100, DL pro, DL DFB           630 – 935 nm*       765 – 795 nm     660
                                        •    Isolator 30 dB, large aperture   1260 – 1395 nm*     815 – 855 nm     760 – 935 nm
                                        +    FiberDock (optional)             1490 – 1610 nm*     915 – 985 nm     1260 – 1395 nm
                                        +    Modulation PCB DL-Mod                                980 – 1075 nm    1490 – 1610 nm

 Configuration III                       Consists of
                                        •    DL 100, DL pro, DL DFB           390 – 420 nm*       765 – 795 nm     660
                                        •    APP compact, compressing         630 – 1180 nm*      815 – 855 nm     760 – 1180 nm
                                        •    Isolator 30 dB                   1260 – 1395 nm*     915 .. 985 nm    1260 – 1395 nm
                                        +    FiberDock (optional)             1490 – 1600 nm*     980 .. 1075 nm   1490 – 1600 nm
                                        +    Modulation PCB DL-Mod

 Configuration IV                        Consists of
                                        •    DL 100, DL pro, DL DFB           650 – 900 nm*       765 .. 795 nm    660
                                        •    Isolator 60 dB, large aperture   1060 – 1090 nm*     815 .. 855 nm    760 – 900 nm
                                        +    FiberDock (optional)             1285 – 1335 nm*                      1060 – 1090 nm
                                        +    Modulation PCB DL-Mod            1515 – 1585 nm*                      1285 – 1335 nm
                                             (optional)                                                            1515 – 1585 nm
 *Please check stock list for diode availability.

 Fixed frequency versions for non-tuning applications
 DL 100/R, DL pro/R: fixed frequency laser – no Piezo actuator, no Scan Control.

 Sample applications for DL/R lasers:
 • Interferometry
 • Holography
 • Raman spectroscopy

 Other custom configurations are available on request.

14   www.toptica.com
                                                                                                                                          Tunable Diode Lasers
Specifications DL Series

                                                                                                                                          Frequency Converted Lasers
Laser                                                      DL 100                      DL pro                     DL DFB
                                                       373 .. 488 nm*                                             660 nm
Center wavelengths                                                             780, 850, 940, 1040 nm
                                                      632 .. 1670 nm*                                          760 – 3000 nm
Typical power range                                     3 .. 220 mW               Max. 50 – 80 mW               2 .. 150 mW
Typical coarse tuning range                              2 .. 80 nm                   ≥ 30 nm                     2 .. 6 nm
Typical mode-hop free
                                                          ≥ 20 GHz                   30 – 50 GHz                  1000 GHz
tuning range
Typical linewidth
                                                        0.1 – 1 MHz                   100 kHz                    0.5 – 4 MHz
(5 µs integration time)
Typical output beam characteristics                                     3 mm x 1 mm, 1 mm x 1 mm with APP C
Beam height                                             53.9 ± 0.5 mm          50 ± 0.3 or 58 ± 0.3 mm          53.9 ± 0.5 mm
Typical polarization                                                            Linear, approx. 100:1

Fiber coupling efficiency**: min. (typ.)                                               55 (65) %
Fiber coupling efficiency with APP**: min. (typ.)                                      65 (75) %
Typical long term frequency change with room
                                                        400 MHz / K                << 100 MHz / K                20 MHz / K
Environment temperature (operating)                                                  15 – 30 °C
Environment temperature (transport)                                                   0 – 40 °C
Humidity                                                                          Non condensing
Operating voltage                                              100 – 120 V / 220 – 240 V AC, 50 – 60 Hz (auto detect)
                                                                                    typ. < 100 W
Power consumption
                                                                                     max. 300 W
Size head (L x W x H)                               228 x 80 x 79.4 mm3          240 x 90 x 90 mm3          228 x 80 x 79.4 mm3
Size electronics (L x W x H)                        400 x 465 x 148 mm3         400 x 465 x 148 mm3         400 x 465 x 148 mm3

                                                                                                                                          Single-Mode Diode Lasers
*Spectral coverage with gaps. **With TOPTICA's FiberDock: -15 % for < 470 nm, efficiency varies when tuning widely with APPs.

The given specifications are obtained with TOPTICA control units DCC 110, DTC 110, and SC 110 in the rack system SYS DC 110.
Actual data strongly depends on the chosen laser diode. TOPTICA offers full assistance in finding the best laser diode for your

                                                                                         How to choose your DL configuration
                                                                                         1. Select suitable laser diode (FP, AR,
                                                                                            DFB – please see pages 4 - 6). Check
                                                                                            diode availability via the appropriate
                                                                                            internet stock list (www.laser-diodes.
                                                                                            com). For DL pro please refer to
                                                                                            page 10. Inquire directly with TOPTICA
                                                                                                                                          Ultrafast Fiber Lasers

                                                                                            for all other wavelengths.

                                                                                         2. Select one of the standard
                                                                                            configurations from page 14,or inquire
                                                                                            about your custom configuration.

                                                                                         3. Contact your local TOPTICA distributor
                                                                                            for an individualized quotation.

      Available standard wavelengths of DL 100, DL pro and DL DFB.

                                                                                                               www.toptica.com       15

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