Optoelectronics Circuits & Systems Lab OCDMA Optical Source Development April 16, 2005 Jason 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 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 Filter

Optoelectronics Circuits & Systems Lab Broadband Spectral Comb Generation ML Laser Line Selection Filter 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 Seed Pulse AWG EDFA DS Fibers DSF 1 DSF 3 DSF 2 p p p Spectrum location is optimized using dispersion slope engineering

Optoelectronics Circuits & Systems Lab Numerical Simulation Starting 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 Output Spectrum Input Seed Conventional Supercontinuum Generation

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.