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SYNOPSIS OF
Generation of tunable, short duration pulses for applications in
time-domain spectroscopy
A THESIS
to be submitted by
AMBIKA NAUTIYAL
for the award of degree
of
DOCTOR OF PHILOSOPHY
DEPARTMENT OF PHYSICS
INDIAN INSTITUTE OF TECHNLOGY MADRAS
CHENNAI- 600036, INDIA
December 2008
1. INTRODUCTION
Ultrashort pulses have attracted a considerable attention due to their numerous
applications such as higher order harmonic generation [Reintjes et al., 1978, and Ferray et al.,
1988] and time-resolved spectroscopy [Fleming, 1986]. During the past decade, optical
parametric amplification (OPA) has been proved to be one of the best techniques for the
generation of the tunable pulses [Ross et al., 1997, Wilhelm et al., 1997, and Yang et al., 2001,
Cerullo et al., 2003]. The non-collinear configuration of OPA (NOPA) has been successfully
implemented for short pulse generation down to sub 5 femtosecond (fs) duration [Kobayashi et
al. 2002]. The concept of non-collinear geometry was introduced first by Gale et al. [Gale et
al., 1995] to obtain the pulses of short duration. Driscoll et al. generated tunable fs pulses in
the range 590 nm-666 nm using second harmonic of the Ti:sapphire laser at a repetition rate of
82 MHz, [Driscoll et al., 1994]. Sum frequency generation has also been used to extend the
tunability range in fs regime [Kozma et al., 2003].
Output of the optical parametric system used for fs pulse generation depends upon the
phase-matching condition [Yariv, 1989], durations of the pump pulse, and the size of the
nonlinear crystal. Pang et al. gave the theoretical analysis of non-collinearly phase-matched
optical parametric amplifier seeded with the white light continuum (WLC) [Pang et al., 2001].
Studies on phase-matching for NOPA process in nonlinear anisotropic crystals have been
carried out by Liu et al. [Liu et al., 2001]. Dependence of the pulse spectrum on the angle
between the pump and the signal beams in optical parametric chirped pulse amplifier with β-
barium borate (BBO, type-I) have been reported [Yang et al. 2001]. Even in the presence of
aforementioned scattered literature on different aspects of parametric processes, there appears
to be a need to reinvestigate the effect of various parameters affecting the OPA process by
making a few sets of experimental data.
Time-resolved spectroscopy of molecular systems is important from the point of view of
physics, chemistry, and biosciences. The ultrashort pulses have several applications in
spectroscopy viz. excited state dynamics [Becker et al., 2001], transient absorption of the species
formed in the excited state, radiative and non-radiative electron transfer and proton transfer
[Fleming, 1986, and Duan et al., 1993]. Microcrystals of fluorescent dyes are the subject of the
study as their fluorescence properties depend strongly upon the size, shape and structural defects
[Bout et al., 1996, Bisht et al., 1997, Sandeep et al., 2006]. In view of the above in this thesis,
1
besides the studies of the generation of tunable ultrashort pulses using OPA and the sum frequency
generation, a model system of pyrene has been chosen for spectroscopic studies.
2. OBJECTIVES AND SCOPE OF THE WORK
2.1. Optical parametric oscillators and amplifiers
When the electric field is applied to a dielectric medium, electric polarization
occurs. At the low intensity levels of light source the relation of the polarization to the
applied field is linear
P = ε 0 χe E (1)
where χ e is the electrical susceptibility and ε0 is the permittivity of free space.
However, when the intensity of the light is sufficiently high (e.g. from a laser) ,
the induced polarization shows a nonlinear dependence on the incident field and can be
written as
⎛ ⎞
Pi = ε 0 ⎜ ∑ χ ij E j + ∑ χ ijk ) E j Ek + ∑ χijkl) E j Ek El + .... ⎟
(2 (3
(2)
⎝ j j ,k j , k ,l ⎠
χij represents the linearity between the induced polarization and the incident electric field.
χijk is the second order nonlinear susceptibility. It is a 3rd rank tensor. It is present in non-
(2)
centro-symmetric materials. χijkl is the third order nonlinear susceptibility. It is a 4th rank
(3)
tensor. E j , Ek , El are the amplitudes of the electric field. The sum frequency generation
(SFG) and the difference frequency generation (DFG) processes are schematically shown in
fig. 1.
ω1 ω3=ω1+ω2 ωi
ωp ωi=ωp-ωs
ω3 (SFG) ωs
ω2 (DFG)
A B
Fig. 1. Schematic of SFG and DFG, where ωp is the pump beam, ωs is the signal beam and
ωi is the idler beam.
2
(2)
The crystals with nonzero value of χ ijk give rise to SFG or DFG under suitable
phase-matching conditions. In SFG, photons with frequencies ω1 and ω2 are annihilated to
create one photon at ω3 .
In OPA a weak signal beam (ωs) along with a strong pump beam (ωp) is
incident on a χ(2) material. Due to destruction of pump photons into two beams, a third
beam called as the idler (ωi) is generated by difference frequency generation (DFG)
along with the signal beam (ωs). Since the signal (ωs) is already present in the system,
it is amplified while propagating through the nonlinear crystal.
Idler
P
Pump
Signal
α Amplified
Pump Signal
Fig. 2. Principle of NOPA .
When the pump is sent at an angle α (fig. 2) in an OPA it is term as NOPA. It has
several advantages such as (i) ease of separation of the signal with the idler [Bhar et al.,
1998], (ii) removal of GVD [Riedle et al., 2000], and (iii) generation of fs pulses.
2.2. Superfluorescence
Superfuorescence is a radiation emitted in a nonlinear optical crystal due to
spontaneous decay of photon of frequency ω3 into frequencies of ω1 and ω2. Therefore, it is
also known as the parametric amplification of the quantum noise. In practice, it is achieved
by pumping a suitable nonlinear crystal. Amplification occurs at those wavelengths for
which the parametric interaction is phase-matched. Smith et al. [Smith et al., 1968] observed
the non-collinear phase-matching in optical parametric noise emission. In 1972, stimulated
parametric fluorescence emission tunable over the range 960 nm to 1160 nm was obtained by
using a barium sodium niobate crystal pumped by frequency doubled Nd3+: glass laser
[Rabson et al., 1972].
3
2.3. White light continuum (WLC)
WLC is a quasi-continuum of light spanning from the ultraviolet through the visible
till near-infrared region. It can be generated when intense ultrashort pulses are focused on a
transparent material. Pulse durations of the pump laser influence the generation mechanisms
of the WLC. Alfano and Shapiro were the first to observe the WLC by focusing powerful
picosecond (ps) pulses into a glass sample [Alfano et al., 1970]. Various mechanisms are
responsible for WLC generation viz., self-phase modulation (SPM), self-focusing, stimulated
Raman scattering (SRS) as well as four photon parametric mixing, and cascading light up-
and down-conversion [Shimizu., 1967, Smith et al., 1977, and Wittmann et al., 1996]. In the
present laboratory Sailaja et al. have studied WLC in water/ D2O mixture on pumping with
ps pulses as well as in sapphire on pumping with fs pulses [Sailaja et al., 2005].
2.4. Coloured conical emission
In optical domain, modulational instability (MI) occurs during light propagation in a
nonlinear medium due to interplay of optical Kerr nonlinearity and group velocity dispersion
which causes exponential growth of perturbation either in time as temporal breakup or in
space as filamentation [Tai et al., 1986]. Optical parametric spectral broadening of ps pulses
has been reported in literature on pumping with 266 nm and 355 nm [Lee et al., 2003]. Zeng
et al. have reported the coloured conical emission in a quadratically nonlinear medium (β-
BBO) under fs pumping [Zeng et al., 2004]. It is observed in the form of exponential growth
of the synchronized signal.
2.5. Photophysics of pyrene microcrystals
Pyrene is well suited for studies on biophysical phenomena like lateral diffusion, inter
or trans-bilayer movement of lipid, and lateral organization of membranes [Somerharhu,
2002]. At higher concentrations, it undergoes excimer formation in nonpolar solution [Birks
et al., 1963]. It has been studied earlier in solutions [Castanheira et al., 1993], films
[Furukawa et al., 1989], and doped microsphers [Fujiwara et al., 2006]. Higher aggregates of
pyrene have been studied in the saturated solutions [Khakhel, 2001].
4
The objectives of the present work include (i) to apply the technique of OPA and sum
frequency generation to generate tunable pulses under ps pumping, (ii) to generate the tunable
conical emission from thick BBO crystals under ps pumping, (iii) to study the effect of non-
collinear angle and thickness on the output of OPA under fs pumping, and (iv) as part of the
applications of ultrashort pulses to the spectroscopy, to study the pyrene single microcrystals by
using steady-state and time-resolved fluorescence microscopy.
3. DESCRIPTION OF THE RESEARCH WORK
3.1. Sum and difference frequency generation
The phase-matching angles for a nonlinear crystal for the sum and difference
frequency generation can be calculated by using the values of refractive indices obtained
from the Sellmeier equations [Kato, 1986]. Eqs (3) & (4) are Sellmeier equations used to
find the ordinary (n0) and extra ordinary (ne) refractive indices for BBO crystal.
0.01878
n0 = 2.7359 +
2
− 0.01354λ 2 (3)
λ − 0.01822
2
0.01224
ne2 = 2.3753 + − 0.01516λ 2 (4)
λ − 0.01667
2
λ is in micrometer.
Fig. 3 gives a typical calculation for the phase-matching angles for DFG for the BBO crystal.
3500 Idler
Signal
Pump: 532 nm
3000 α = 2.2
0
Wavelength (nm)
Fig. 3. Tunings curve for phase matching in a non-collinear
2500
geometry for signal and idler wavelengths when pumped with 2000
Idler
532 nm (α=2.20). 1500
1000
Signal
500
22.5 23.0 23.5 24.0 24.5 25.0 25.5
Phase matching angle (θ) (degrees)
3.2. Generation of broadly tunable emission from thick BBO crystal
Picosecond pulses from a Nd+3:YAG laser at 532 nm with pulse energies of 2 mJ
were focused by a concave mirror of 500 mm focal length on a BBO crystal (fig. 4).
5
Pump
θ
Fig. 4. Schematic of the experimental setup for conical
emission. M1 is the concave mirror. θ is the tilt angle φ Pump
of the BBO crystal from the vertical. φ is the angular spot
position of the detector. M1 Detector
plane
Coloured emissions were observed at the detector plane. At smaller tilt angles, the
angular positions of the observed colours were found to be the function of their frequencies.
The propagation angle ( φ ) with respect to the pump beam can be given by the relation
[Luther et al., 1994]
"
φ = k0 k Ω (5)
0
where, k0 = 2π n
λ0 , (λ0 is the pump wavelength and the n is the refractive index of the
"
optical medium), k 0 is the group velocity dispersion and Ω is the difference of the
generated (ω) and the input (ω0) frequencies.
Table 1 gives the observed positions (φ) of some of the radiations for crystal tilt (θ)
fixed at 60. The calculated values of φ for the emissions (by using eq. (5)) are also given for
the comparison. It is seen that the calculated values of φ match reasonably well with those
obtained experimentally.
Table 1. Observed and calculated values of φ of the radiations at the crystal tilt angle of 60.
Obtained wavelength Observed angular Calculated angular
± 2 nm positions ± 0.5 0 positions ± 0. 30
941 6.8 7.0
844 5.8 5.6
550 0.5 0.5
424 -4.3a -3.6a
a). Negative sign indicates that the radiation was observed below the pump spot.
6
3.3. Generation of white light continuum (WLC)
The fundamental of Nd+3:YAG laser was used to obtain the WLC. The water/D2O
mixture [Sailaja et al., 2005], or water alone was used in a 100 mm long glass cell. The
spectra of the WLC generation in water under ps and fs pumping ( in sapphire) are shown in
fig. 5.
1.0
A 1.0 B Pump
0.8
Normalised Intensity
Normalised Intensity
0.8
(arb. units))
0.6
(arb. units)
0.6
0.4
0.4
0.2
0.2
0.0 0.0
400 500 600 700 800 400 500 600 700 800
Wavelength (nm)
Wavelength (nm)
Fig. 5. The spectra of the WLC in water under ps pumping (Panel A), and in sapphire (2 mm
thick) under fs pumping (Panel B).
3.4. Generation of tunable pulses by sum frequency generation
The spectra obtained from the sum frequency generation of the WLC and the
fundamental wavelength of the Nd+3:YAG laser are shown in fig. 6. The spectra were
obtained in collinear geometry within a 40 tilt of the BBO crystal (cut angle 21.90). Tunable
pulses from 440 nm - 520 nm in the ps regime were obtained. Amplification of the
fundamental wavelength of the laser and the portion of the WLC were also obtained.
1.0
Intensity (arb .units)
0.8
Fig. 6. Spectra obtained from the sum-frequency 0.6
generation of the WLC and 1064 nm. 0.4
0.2
0.0
440 460 480 500 520
Wavelength (nm)
7
3.5. Experimental set up for the amplification of WLC under fs pumping
A set up for the single-stage amplification of the WLC under fs pumping was
fabricated in the laboratory during the course of this work (fig. 7). In this set up, the pump is
sent at angle to the amplifying crystal to get rid of the dispersion effect. Therefore the
geometry is known as non-collinear optical parametric amplifier (NOPA).
NOPA A2
A1 S crystal
F WLC Idler
M1
Amplified signal
L1 L2 M3 400 nm
800 nm
400 nm + 800 nm
800 nm, 100 fs, 1 KHz BS BBO(1) M2 BD
Fig. 7. Experimental setup for femtosecond NOPA. M1, M2: plane mirror, M3: focusing
mirror, BS: beam splitter, BD: beam dump, BBO(1): SHG crystal, F: filter to block 1064 nm,
L1, L2: lens, S: sapphire, A1, A2: aperture.
This set up requires at least 300μJ energy pump pulses. Therefore it was transported
to Raja Raman center for advanced technology, Indore to work with amplified pulses. Fig.
8A shows the typical spectra obtained from this setup. The pulse width of the spectra was
estimated from the half widths using the relation Δt = 0.441λ 2 .
cΔλ
35
Normalised Intensity (arb. units)
1.0
A B
30
0.8
Pulse-duration (fs)
25
0.6
20
0.4
15
0.2
10
0.0
480 510 540 570 600 630 660 480 500 520 540 560 580 600 620
Wavelength (nm)
Wavelength (nm)
Fig. 8. Panel A: Tunable output obtained from fs NOPA on variation of the phase-matching
angles of the NOPA crystal. Plot of estimated pulse-width as a function of the wavelength
(Panel B).
8
Simulations were made for the non-collinear angles as a function of the signal
wavelength for the pump wavelength of 400 nm. It was observed that non-collinear angle
varies from 2.60 to 3.80 for the signal wavelength ranging from 500 nm to 700 nm.
3.6. Spectroscopy of single microcrystals of pyrene
As a part of spectroscopic applications of ultrashort tunable lasers (undergoing in the
laboratory), a few photophysical systems were studied. One of them viz., a model system of
the pyrene, was chosen for the detailed work in single microcrystals.
Fig. 9 gives the fluorescence spectra of pyrene obtained from a concentrated solution
and from a single microcrystal. In contrast to broad structureless spectrum of excimer, a
vibrational structure is seen in the fluorescence spectrum of the microcrystal. The inset of the
fig. 9 shows the fluorescence image of a single microcrystal of pyrene upon excitation with the
mercury lamp.
1.0 a: 443 nm
1.0 A B b: 465 nm
Fluorescence Intensity
0.8
Fluorescence Intensity
c: 503 nm
0.8 5μm b c d: 535 nm
(arb. units)
0.6 e: 570 nm
(arb. units)
0.6 b a
0.4 a
0.4
d
0.2 0.2
e
0.0 0.0
400 450 500 550 600 400 450 500 550 600
Wavelength (nm) Wavelength (nm)
Fig. 9.Panel A: Fluorescence spectrum of pyrene microcrystal of size 12.5 x 15 μm2 (a) and
pyrene in cyclohexane (5 x 10-2 M) (b). Inset gives the fluorescence image of a pyrene
microcrystal (20 x 30 μm2). Panel B: Gaussian fitting of the microcrystal emission gives at
least 5 spectra.
Emission wavelength dependence of the decay times of the fluorescence of the single
microcrystals was studied. It was observed that fluorescence lifetimes increase with the emission
wavelength. This indicates towards the sites selectivity within the microcrystal that results in
various emission components. Fig. 10 shows the fluorescence decay measured with TCSPC
system with two different excitation wavelengths. It is due to the fact that in solution the
absorption spectra do not extend beyond 360 nm, while the single crystals can be measured
under a microscope where only 408 nm ps laser is available for excitation.
9
1000 λ ex= 408 nm 10000
A B
τ1 =4.90 ns; B 1=0.15 λ ex = 340 nm
τ2 =15.0 ns; B 1=0.14
100
1000 τ 1 = 12 ns; B 1=-1.10
Counts
Counts
τ 2 = 14 ns; B 2= 1.10
10 IRF IRF
100
1
3 C D
Residuals
2
Residuals
0 0
- 2
- 3
2 0 4 0 6 0 8 0 2 0 4 0 6 0 8 0 1 0 0
T i m e ( n s ) T i m e ( n s )
Fig. 10. Panel A. Fluorescence decay of the single pyrene microcrystal (size= 25x 50 μm2)
(Panel A), of pyrene solution (10-3 M, Panel B). Panels C and D, respectively show the
residuals for double exponential fit.
It was observed that while the concentrated pyrene solution gives the well known
excimer emission, the single microcrystal spectra are red shifted but have no indications for
the excimer emissions.
4. CONCLUSIONS
(1). Tunable output from the thick BBO crystal was obtained in single pump-beam crystal-
tilt geometry.
(2). Amplification of the fundamental from Nd+3: YAG laser was obtained on pumping with
the 532 nm.
(3). Tunable pulses from 440 - 520 nm were obtained from the sum frequency generation of
the fundamental of the ps Nd+3:YAG laser and the WLC in the collinear geometry.
(4). Dependence of the fs NOPA output on non-collinear angle and the thickness of the
BBO crystal was studied by simulations after taking the single set of experimental data.
(5). Steady-state and time resolved studies on pyrene microcrystals show the overlap of various
spectra and the self-absorption effects in fluorescence lifetime. This is in contrast to the
behaviour in solutions phase where excimer formation takes place in highly concentrated
solutions.
10
REFERENCES
1. Alfano, R. R., and S. L. Shapiro, (1970), “Emission in the region 4000 to 7000 A0 via
four-photon coupling in glass, Phy. Rev. Lett., 24, 584-587.
2. Becker, W., A. Bergmann, K. Koeing, and U. Tirlapur, (2001), “Picosecond
fluorescence lifetime measurement by TCSPC imaging”, Proc. SPIE, 4264, 414-419.
3. Bhar, G. C, P. Kumbhakar, U. Chatterjee, A. M. Rudra, Y. Kuwano, and H. Kouta,
(1998), “Efficient generation of 200-230 nm radiations in beta barium borate by non-
collinear sum frequency mixing”, Appl. Opt., 37, 7827-7831.
4. Birks, J. B., and L. G. Chirstophorou, (1963), “Excimer fluorescence of pyrene
derivatives”, Spectrochim Acta., 19, 401-410.
5. Bisht, P. B., K. Fukuda, and H. Hirayama, (1997), “Size dependent fluorescence
emission spectra and lifetimes of microcrystals of DBPI studies by confocal fluorescence
microscopy”, J. Phys. Chem., 101, 8054-8058.
6. Bout, D. A. V., J. Kerimo, D. A. Higgins, and P. F. Barbara, (1996), “Spatially resolved
spectral inhomogeneities in small molecular crystals studied by near-field scanning optical
microscopy”, J. Phys. Chem., 100, 11843 - 11849.
7. Castanheira, E. M. S., and J. M. G. Martinho, (1993), “Thermochromic shifts of pyrene
excimer fluorescence” Chem. Phys. Lett., 206, 45-48.
8. Cerullo, G. and S. D. Silvestri, (2003), “Ultrafast optical amplifiers”, Rev. Sci. Instrum.,
74, 1-18.
9. Driscoll, T. J., G. M. Gale, and F. Hache, (1994), “Ti:sapphire second-harmonic-pumped
visible range femtosecond optical parametric oscillator”, Opt. Commun., 110, 638-644.
10. Duan, X., and S. Schinier, (1993), “Ground and excites state intra-molecules proton
transfer in OCCNN ring”, Chem. Phys. Lett., 204, 36-44.
11. Ferray, M., A. L. Huillier, X. F. Li, L. A. Lompre, G. Mainfray, and C. Manus,
(1988), “Multiple-harmonic conversion of 1064 nm radiation in rare gases”, J. Phys. B: At.
Mol. Opt. Phys. , 21, L31-L35.
12. Fleming, G. R., (1986), “Chemical Applications in Ultrafast Spectroscopy”, Oxford
University press, New York.
13. Fujiwara, H., K. Sasaki, and H. Masuhara, (2006), “Enhancement of forster energy
transfer within a microcavity”, Chem. Phys. Phys Chem., 6, 2410-2416.
11
14. Furukawa, H., K. Mizuno, A. Matsui, N. Tamai, and I. Yamazaki, (1989),
“Branching of exciton relaxation to free and self trapped exciton states”, Chem. Phys., 138,
423-432.
15. Gale, G. M., M. Cavallari, T. J. Driscoll, and F. Hache, (1995), “Sub- 20-fs tunable
pulses in the visible from an 82 MHz optical parametric oscillator”, Opt. Lett., 20, 1562-1564.
16. Kato, K., (1986), “Second harmonic generation to 2048 Ao in β-BaB2O4”, J. Quan.
Electron., 22, 1013-1014.
17. Khakhel, O. A., (2001), “Absorption spectra of pyrene aggregates in saturated solutions”,
J. App. Spect., 68, 280-286.
18. Kobayashi, T., and A. Baltuska, (2002), “Sub-5 fs pulse generation from a
noncollinear optical parametric amplifier’, Measur. Sci. Tech., 13, 1671-1682.
19. Kozma, I. Z., P. Baum, S. Lochbrunner, and E. Riedle, (2003), “Widely tunable
sub–30 fs ultraviolet pulses chirped sum frequency mixing”, Opt. Exp., 11, 3110 - 3115.
20. Lee, S. M., B. K. Rhee, M. Choi, and S. Park, (2003), “Optical parametric spectral
broadening of picosecond laser pulses in β-barium borate”, App. Phys. Lett., 83, 1722-1724.
21. Liu, H. J., G. F. Chen, W. Zhao, Y. S. Wang, T. Wang, and S. H. Zhao, (2001),
“Phase matching analysis of non-collinear optical parametric process in nonlinear anisotropic
crystals” Opt. Commun., 197, 507-514.
22. Luther, G. G., A. C. Newell, and J. V. Moloney, (1994), “ Short –pulse conical
emission and spectral broadening in normally dispersive media”, Opt. Lett., 19, 789-791.
23. Pang, D., R. Zhang, and Q. Wang, (2001), “Theoretical analysis of noncollinear phase-
matched optical parametric amplifier seeded by a white-light continuum”, Opt. Commun.,
196, 293-298.
24. Rabson, T. A., H. J. Ruiz, P. L. Shah, and F. K. Tittel, (1972), “Stimulated parametric
fluorescence induced by picosecond pump pulses”, App. Phy. Lett., 21, 129-131.
25. Reintjes, J., C. Y. She, and R. C. Eckardt, (1978), “Generation of coherent radiation
in XUV by fifth and seventh order frequency conversion in rare gases”, J. Quan. Electron.,
14, 581-596.
12
26. Riedle, E., M. Beutter, S. Lochbrunner, J. Piel, S. Schenkl, S. Sporlien, and W. Zinth,
(2000), “Generation of 10 to 50 fs pulses tunable through all the visible and
NIR,” App. Phys. B, 71, 457 - 464.
27. Ross, I. N., P. Matousek, M. Towrie, A. J. Langley, and J. L. Collier, (1997), “The
prospect for ultrashort pulse duration and ultrahigh intensity using optical parametric
chirped pulse amplifier,” Opt. Commun., 144, 125 – 133.
28. Sailaja, R., V. Sreeja, and P. B. Bisht, (2005), “Studies of self-phase modulation
under cw and Picosecond laser pumping: white light continuum generation in water”, Ind. J.
Phys., 79, 1299 - 1302.
29. Sandeep, P., and P. B. Bisht, (2006), “Photophysics of 9-amino acridine hydrochloride
hydrate single microcrystals”, Chem. Phys., 326, 521-526.
30. Somerharhu, P., (2002), “Pyrene labeled lipids as tools in membrane biophysics and cell
biology”, Chem. Phys. Lipd., 116, 57-74.
31. Shimizu, F., (1967), “Frequency broadening in liquids by a short light pulse”, Phys. Rev.
Lett., 19, 1097-1100.
32. Smith, R. G., J. E. Geusic, H. J. Levinstein, J. J. Rubin, S. Singh, and L. G. Van
Uitert, (1968), “Continuous optical parametric oscillations in Ba2NaNb5O15”, App. Phy.
Lett., 12, 308-310.
33. Smith, W. L., P. Liu, and N. Bloembergen, (1977), “Superbroadening in H2O and
D2O by self-focused picosecond pulses from a YAlG: Nd laser”, Phys. Rev. A, 15, 2396-2403.
34. Tai., K., A. Hasegawa, and A. Tomita, (1986), “Observation of modulational instability in
optical fibers”, Phys. Rev. Lett., 56, 135-138.
35. Wilhelm, T., J. Piel, and E. Riedle, (1997), “Sub-20-fs pulses tunable across the visible
from a blue-pumped single pass non-collinear parametric converter”, Opt. Lett., 22, 1494-1496.
36. Wittmann, M., and A. Penzkofer, (1996), “Spectral superbroadening of femtosecond
laser pulses”, Opt. Commun., 126, 308-317.
37. Yang, X., Z. Xu, Zhang, Y. Leng, J. Peng, J. Wang, S. Jin, W. Zhang, and R. Li,
(2001), “Dependence of Spectrum on pump signal angle in BBO-I non-collinear optical
parametric chirped pulse amplification”, Appl. Phys. B., 73, 219 - 222.
38. Yariv, A., (2006), “Quantum Optics”, John Wiley, New-York.
39. Zeng, H., J. Wu, H. Xu, K. Wu, and E. Wu, (2004), “Colored conical emission by
13
means of second harmonic generation in a quadractically nonlinear medium”, Phys. Rev. Lett.,
92, 143903-1 - 143903-4.
PROPOSED PLAN OF THE THESIS
Chapter 1: Introduction
Chapter 2: Experimental details
Chapter 3: Tunable pulse generation from sum and difference frequency generation of
white light continuum with the fundamental of the picosecond Nd+3:YAG laser
Chapter 4: Generation of tunable line emission from β - barium borate on pumping with
picosecond pulses
Chapter 5: Study of the parameters affecting the output of femtosecond pulse generation by
non-collinear optical parametric amplification
Chapter 6: Photophysics of pyrene single microcrystals
Chapter 7: Conclusions
VISIBLE OUTPUT BASED ON THE RESEARCH WORK
Refereed Journals
1. “Sum and difference frequency generation of white light continuum with the ps pulses of
Nd+3:YAG laser in a thick BBO crystal”, A. Nautiyal and P. B. Bisht, Opt. Commun. 278
(2007) 175-179.
2. “Broadly tunable parametric line emission from β - barium borate on pumping with
picosecond pulses”, A. Nautiyal and P. B. Bisht, Opt. Commun. 281 (2008) 3351-3355.
3. “Recent developments in optical parametric amplifiers and characterization of ultrafast
pulses”, A. Nautiyal and P. B. Bisht, "Nonlinear Optics Research Progress" Nova Science
Publishers, Inc. (In press, 2008).
4. “Effects of thickness of β-barium borate and angle of non-collinearity on the fs pulse
generation by optical parametric amplification”, A. Nautiyal, P. B. Bisht, K. S. Bindra and S.
M. Oak (Optics & Laser Technology, in press, 2008).
5. “Steady state and time-resolved studies of pyrene in solution and in single microcrystals”,
A. Nautiyal and P. B. Bisht (Communicated, J. Photochem. and Photobio. A).
14
National Conferences
1. “Design parameters of femtosecond non-collinear optical parametric amplifier”, A. Nautiyal
and P. B. Bisht, Proc. of National Laser Symposium (N L S), held at IIT Kharagpur, Dec. 22-24,
2003, pp. 445.
2. “A single stage tunable femtosecond non-collinear optical parametric amplifier for visible-
UV-near IR applications”, A. Nautiyal and P. B. Bisht, Proc. of National Laser Symposium
(NLS-4), held at BARC, Mumbai, Jan. 10-13, 2005, pp. 299.
3. “Ultrafast pulse genaration for spectroscopy: non-collinear optical parametric amplification”
A. Nautiyal and P. B. Bisht, Proc. of National Symposium on Radiation and the Photochemistry
(NSRP), held at Karnataka University, Dharwad, Jan 17-19, 2005, PC-41.
4. “Resolution of a micrometer by confocal fluorescence microscopy in laser embedded
multi layer polymer films”, A. Nautiyal, P. Sandeep and P. B. Bisht, Proc. of the National
Symposium on Radiation and the Photochemistry (NSRP), held at Karnatak University,
Dharwad, Jan 17-19, 2005, PC-40. (It was selected as the one of the best posters among the
first four).
5. “Design and operation of a femtosecond non-collinear optical parametric amplifier”,
A. Nautiyal, P. B. Bisht, K. S. Bindra, and S. M. Oak, Proc. of National Laser Symposium
(NLS-5 ),held at VIT, Vellore, Dec 7-10, 2005, poster No. 54.
6. “Generation of tunable femtosecond pulses with non-collinear optical parametric
amplifier fabricated at IIT Madras”, A. Nautiyal, K. S. Bindra, and S. M. Oak, P. B. Bisht,
Proc.of Progress on Tunable Lasers for Ultrafast Processes and Applications (PTLUPA6),
held at IIT Madras, Dec. 21-22, 2006, pp 40-41.
7. “Sum frequency generation and parametric amplification of white light continuum generated
from water – D2O mixture under picosecond pumping”, A. Nautiyal, and P. B. Bisht, Proc.of
Progress on Tunable Lasers for Ultrafast Processes and Applications (PTLUPA6), held at IIT
Madras, Dec. 21-22, 2006, pp 42 - 43.
8. “Time resolved spectroscopy of pyrene microcrystals”, A. Nautiyal, and P. B. Bisht,
Proc. of India-Singapore symposium on currents trends in physics, held at IIT Madras, Feb.
28-Mar. 01, 2008, poster No. 18.
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9. “Tunable emission from β-barium borate by optical parametric amplification, four wave
mixing, and second harmonic generation”, A. Nautiyal, and P. B. Bisht, One day semiar on
photonics, IITM SPIE students chapter, held at IIT Madras, Dec. 4, 2008, pp 31-32.
International Conference
1. “Novel technique for generation of tunable emission from β - barium borate”, A. Nautiyal,
and P. B. Bisht, International Conference on Functional Materials for Advanced Technology, Jan
29-30, 2009, to be held at Chennai (accepted for oral presentation).
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