Self-consistent static nonlinear screening in quantum-Hall bars by yurtgc548

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									  Development of broadband
    Er-doped fibersource

           PHYS 492 Senior Project
               by Hasan Esat KONDAKÇI
Department of Physics, Bilkent University, Bilkent, Ankara
Outline
 Introduction
 Basics and concepts
   Amplifier Gain
   Power Source
   Gain Saturation
 Experiment
   Experimental Setup
   Meanwavelength
    temperature
    dependence
   Pump power
    efficiency
 Conclusion
   Brief Summary
Introduction

 A coherent optical amplifier is a device that
  increase the amplitude of an optical field while
  maintaining its phase.
 COP’s are important for various apllications;
  amplification of weak optical pulses such as
  those that travel through long a long length if
  optical fiber
Basics and Concepts

  There are three
  types of photon-
  atom interactions
 Absorption of
  photons
 Stimulated
  emission
 Spontaneous
  emission
Amplifier Gain


Underlying principle for achieving the coherent
   amplification of light is light amplification
   by the stimulated emission of radiation
 in the process we get clone photon with
   same frequency, direction and polarization
 two photons can serve to stimulate the
   emission two additional photons and so on
 result is coherent light amplification
Amplifier Gain (Cont’d)

 Coherent light amplification is due to when
  photon energy is nearly equal to the atomic
  transition energy level
 Essential is the presence of a greater
  number of atoms in the upper energy level
 Achieving such a population inversion
  requires a source of power to excite (pump)
  the atoms into the higher energy level
Amplifier Power Source

Laser amplifiers require an external source of
   power to provide energy
 The pump must provide a population
   inversion on the transition of interest
 Pumping may be achieved optically,
   electrically, chemically even by nuclear
   expansion
 Required conditions determined by rate
   equations which depends laser gain medium
Amplifier Power Source (Cont’d)

 Rare-earth-doped silica fibers cab serve as
  useful amplifying media.
 Erbium doped fibre amplifier is the most
  deployed fibre amplifier
 Pumping is achieved by transmitting laser
  light
Gain Saturation

 Ideal amplifiers have linear system that
  increases the amplitude of the input signal
  by a fixed factor, called amplifier gain
 Real coherent amplifiers deliver a gain
  frequency dependent
 For sufficiently high input amplitude real
  amplifiers may exhibit saturation
 Fails to increase in proportion to input
  amplitude
Experiment
 ASE source experimental setup
Forward Port Spectrum
Backward Port Spectrum
Forward Port Temperature Dependence




 Pump diode current = 75mA   Pump diode current = 100mA
 m= -5.34+/-1.11 ppm/C       m= -0.813+/-0.609 ppm/C
Backward Port Temperature Dependence




 Pump diode current = 75mA   Pump diode current = 100mA
 m= 6.30+/-1.91 ppm/C        m= 2.90+/-0.37 ppm/C
Output power vs pump power

                             Forward port
                             m=0.057
                             Efficiency=%5.7


                             Backward Port
                             m=0.094
                             Efficiency=%9.4


                             Total eff=%15.1
Labview Interface
Labview Block Diagram
Conclusion

  Linear temperature dependence
  Without saturation pumping in the
   range 0-500 mW for 175 cm Er
   doped fiber silica
References;



   http://www.sp.phy.cam.ac.uk/~SiGe/Stimulated%20Emission.
    html
   Bahaa E. A. Saleh, Malvin Carl Teich "Fundamentals of
    Photonics”
   Frank L. Pedrotti, Leno S. Pedrotti, Leno M. Pedrotti
    “Introduction to Optics“
   E. Desurvire "Rare-Earth Doped Fiber Lasers and Amplifiers"
 Thank you for your attention
Questions


 ???
 ??
 ?

								
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