Broadband Lateral Tapered Structures for Improved Bandwidth and Loss Characteristics for All-Optical Wavelength Converters Xuejin Yan, Joe Summers, Wei Wang, Marcelo Davanco, Wenbin Zhao, Milan Masanovic, Vikrant Lal, and Daniel Blumenthal Electrical and Computer Engineering University of California at Santa Barbara

Summary of Work Objective: Develop building blocks to extend tuning range and decrease insertion loss of SOA XPM tunable wavelength converter to 30nm tuning range at 1.55m wavelength. Approach: Monolithically Integrate SOA wavelength converter with Mach-Zehnder structure with tunable laser using based-InP material. Major accomplishments: 1) Designed new type of broadband splitter/combiner for WC. 2) Active/passive structures have been designed for same structures. 2) Splitter loss was measured to be better than MMI and Y-splitter over a wavelength range of 100nm. 3) Active XGM was demonstrated using this design. 4) A TWC has been designed and basic DC functionality demonstrated. 5) low reflection and low loss coupling techniques have been designed and fabricated: (i) a window design and (ii) a tapered mode converter

Outline Mach-Zehnder SOA wavelength converter with new waveguide structure. The splitter with lateral tapers The vertical coupler at the interface of active to passive waveguide The mode-shape converter with lateral taper and InP windows XGM results Tunable wavelength converter(WC with integrated tunable laser). The structure of the TWC The initial results Issues Future work

The picture of WC

Splitter and combiner Waveguide layer InP Substrate

The picture of the splitter

Near Field Image of Splitter Distance between two spots is 250 m

Near Field Image of Splitter with InP Window

Wavelength sensitivity of the splitter

The spectrum of the splitter with integrated SOA

Active to passive vertical transformer Active layer InP etching stop layer Waveguide layer InP Substrate

The Vertical Coupler

InP window and mode-shape converter Lateral taper InP window InP Substrate