optoelectronics circuits systems lab ocdma optical source development april 16, 2005 jason chou,...
DESCRIPTION
Optoelectronics Circuits & Systems Lab SC-enhanced Mode Locked Source MLL EDFA DS Fiber Requires only a few longitudinal modes from the mode locked laser Simplifies design Extend the spectrum to create a broad comb of frequencies of multi-THz bandwidth by super-broadening Decouples the laser design from the spectrum requirement of OCDMA FilterTRANSCRIPT
Optoelectronics Circuits & Systems Lab
OCDMA Optical Source Development
April 16, 2005Jason Chou, Ozdal Boyraz, and Bahram Jalali
University of California, Los Angeles
Optoelectronics Circuits & Systems Lab
Goal Conventional supercontinuum source
produces broadband spectrum, where only small portion is used
Goal is to create spectrum only where it is needed
Approaches:• Broadband comb generations • Asymmetric comb generation
Optoelectronics Circuits & Systems Lab
SC-enhanced Mode Locked Source
MLL
EDFADS Fiber
• Requires only a few longitudinal modes from the mode locked laser• Simplifies design
• Extend the spectrum to create a broad comb of frequencies of multi-THz bandwidth by super-broadening• Decouples the laser design from the spectrum requirement of OCDMA
Filter
Optoelectronics Circuits & Systems Lab
Broadband Spectral Comb Generation
MLLaser
Line SelectionFilter
EDFA
p p p
DS Fiber
•Desired lines are selected from MLL spectrum•Act as seed for generating desired spectral lines•Generation achieved using SPM and FWM in nonlinear media
Optoelectronics Circuits & Systems Lab
Asymmetric Broadband Spectral Comb Generation
SeedPulse AWG
EDFA DS Fibers
DSF1 DSF3DSF2
p p p
•Spectrum location is optimized using dispersion slope engineering
Optoelectronics Circuits & Systems Lab
Numerical SimulationStarting Spectrum After FWM in single mode fiber
Optical Frequency
Asymmetry
•Asymmetry in spectrum can be induced through dispersion slope•Effect is modest in standard single mode fiber•Can be drastic in dispersion engineered media
Optical Frequency
Optoelectronics Circuits & Systems Lab
Experimental Demonstration
•Independent control of channel separation and total bandwidth•Power is concentrated in discrete OCDMA channels •>25nm bandwidth•Promising approach
-40
-30
-20
-10
0
10
20
30
40
1525 1530 1535 1540 1545 1550 1555 1560 1565 1570 1575
Wavelength [nm]
Pow
er [d
Bm
/nm
]
Output Spectrum
InputSeed
PC
=1300nm =1490nm =1561nm
BPF
MLL EDFA
Modulator
Input RF Signal
Chirped Optical Pulse
DispersionWav
elen
gth
Time
Optical BW
Stretched RF Signal
PDSCSource
Dispersion
Fiber L1 Fiber L2
1500 1520 1540 1560 1580 1600 1620-30
-25
-20
-15
-10
Ampl
itude
(a.u
.)
Wavelength (nm)
PC
=1300nm =1490nm =1561nm
BPF
MLL EDFA
PC
=1300nm =1490nm =1561nm
BPF
MLL EDFA
Modulator
Input RF Signal
Chirped Optical Pulse
DispersionWav
elen
gth
Time
Optical BW
Stretched RF Signal
PDSCSource
Dispersion
Fiber L1 Fiber L2
1500 1520 1540 1560 1580 1600 1620-30
-25
-20
-15
-10
Ampl
itude
(a.u
.)
Wavelength (nm)
1500 1520 1540 1560 1580 1600 1620-30
-25
-20
-15
-10
Ampl
itude
(a.u
.)
Wavelength (nm)
Conventional SupercontinuumGeneration
Optoelectronics Circuits & Systems Lab
Next Steps Dispersion engineering will be investigated by cascading
fibers with dispersion tailored profiles to improve efficiency and flatten channel profile.
Dynamic range per channel is limited by ASE-FWM beating effect which can be mitigated by adding narrowband optical filters to suppress EDFA noise background.
Alternative approach to improve FWM efficiency and reduce noise is to filter and overlap MLL pulses before passing through dispersion engineered fibers.