Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Focus Areas Photonic Signal Processing Planar waveguide devices Research Team: Professors K. T. Chan, Chester Shu, Hon Tsang, Chinlon Lin + 4 research staff + 15 graduate students Optoelectronic Laboratory

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Examples of Research Output All-optical signal processing –Photonic ADC –Polarization diversity loop for polarization insensitive operation –Wavelength conversion using FWM in SOA Birefringence Switching Dual wavelength injection locking –Data Modulation Format Conversion (RZ to NRZ and NRZ to RZ) –OTDM demultiplexing Waveguides –Polarization dependent frequency and polarization dependent loss compensation via FIB trimming Magnetostrictive layer deposited on waveguide –InGaAsP Waveguide Fabry-Perot filter (high speed tuneable via current injection) –Nonlinear Applications of SOI waveguides : Raman Amplification –Material properties (measure dispersion, Kerr effect & TPA in SOI waveguides) Ultrafast optics and nonlinear optics –Spectral measurement in time domain using dispersion –Two photon autocorrelation using InGaAsP and Si waveguides –Terahertz pulse generation and detection using ion implanted GaAs T.K.Liang and H.K.Tsang, APPL PHYS LETT 81 (7): 1323 AUG 2002

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Sampling in optical domain and quantization in electronic domain Optical Source Sampling Transducer quantization Optical Demux Digital signal processor quantization : electrical signal : optical signal Microwave signal Optical Source : Time and wavelength-interleaved pulses Photonic ADC Lee KL, Shu C: “ Switching-wavelength pulse source constructed from a dispersion-managed SOA fiber ring laser” IEEE PHOTONICS TECHNOLOGY LETTERS 15 (4): APR 2003 / Fiber laser

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong 10 channel output from 1 = to 10 = nm Channel spacing: 1.03 nm Suppression of non-lasing mode > 20 dB 10 Gigasample/s Photonic ADC using 10-wavelength sampling pulses Overall repetition rate: 10 GHz Individual operated at 1 GHz Pulse width: ps Timing jitter < 0.2 ps

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong All-optical wavelength conversion M.W.K. Mak, H.K. Tsang and K.Chan: “Widely tunable polarization-independent all-optical wavelength converter using a semiconductor optical amplifier,” IEEE Phot. Tech. Lett., vol.12, (2000) 40 Gb/s wavelength conversion Received optical power (dBm) log(BER) 0.9 dB Back-to-back Converted

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Wavelength conversion: BOP FWM without external optical pump Pump 1 Output SOA Signal Pump 2 K. K. Chow, C. Shu, M. W. K. Mak and H. K. Tsang, “Widely tunable wavelength converter using a double-ring fiber laser with a semiconductor optical amplifier,” IEEE Photonics Technology Letters, vol. 14, pp , October 2002.

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Tunable 40Gbit/s optical source HDF SOA PC2 Isolator FFP Optical Coupler OC C PC1 FPLD RF Synthesizer Output Dispersive frequency multiplication Mode-locked SOA fiber-ring laser Mark W.K.Mak and H.K.Tsang: “Dispersive Frequency Multiplication for Wavelength-Tunable High Repetition Rate Pulse-Train Generation,”Optical Fiber Communications 2001 (Anaheim), 2001.

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Optical CDMA Wang X, Lee KL, Shu C, Chan KT: “Multiwavelength self-seeded Fabry-Perot laser with subharmonic pulse- gating for two-dimensional fiber optic-CDMA,” IEEE PHOTONICS TECHNOLOGY LETTERS 13 (12): DEC 2001

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong High speed tunable filter Tunable waveguide filter H.K. Tsang et al. “ Etched Cavity InGaAsP/InP Waveguide Fabry-Perot Filter Tunable by Current Injection,” IEEE J. Lightwave Tech, vol.17, p (1999)

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Polarization compensation by magnetostriction Magnetostriction: anisotropic strain induced by magnetic field Saturation Magnetostriction constant ( ) =fractional change in length External Magnetic field direction y x Silicon Thermal oxide Buried Oxide Silicon Thermal oxide Ferromagnetic film Buried Oxide Silicon P.S. Chan, H.K. Tsang, “Magnetostrictive Polarization Compensation on SOI Rib Waveguide”, 8th OptoElectronics and Communications Conference, Shanghai, China, Oct 2003.

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Focused Ion Beam Etching for mode conversion and PDF adjustment P.S. Chan, H.K. Tsang, C. Shu, “Mode Conversion and Birefringence Adjustment via Focused Ion Beam Etching for Slanted rib Waveguide walls”, to appear in Optics Lett. Nov Gallium Ion Side view of trimmed portion of rib. Top view of trimmed rib SOI waveguide by 45 degrees, 10m Wavelength (nm) Output power (dBm) TE TM Compensated by 10um FIB trimming WITHOUT compensation

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Silicon oxynitride switch A Zhang and KT Chan “Characterization of the optical loss of an integrated silicon oxynitride optical switch structure,” Appl. Phys. Lett., Vol. 83, No. 13, 29 September 2003 trench for liquid crystal material for switching

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong New topics of current interest Raman gain in silicon waveguides (HK Tsang) Quantum encryption using multiphoton entanglement generated from spontaneous parametric down conversion (KT Chan) Photonic Crystal Fibers for signal processing and sensors (CT Shu) Si SiO 2 Si (substrate) n+n+ p+p+ DFB Laser Monochrometer Power Meter Coupler waveguide Stokes (nm)

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Future Directions in planar waveguides & nanophotonics Possible future directions: –Miniaturization of planar waveguide components using silicon wires Requires considerable investment to improve dry etching capability (HKUST equipment is inadequate for etching submicron waveguides) Work needed on improving coupling loss and polarization dependence –Periodic structures (thin film photonic crystal)? From Richard M. De La Rue “Photonic Crystal and Photonic Wire Devices and Technology” ECOC 2003 “The technological problems involved in fabrication with sufficient precision and acceptable propagation losses continue to present a major challenge for device engineers and physicists.” “… the likely impact of photonic crystal and photonic wire…is considerable. Within a small number of years, we are likely to witness moderately high volume production of devices which will incorporate the thinking that has been developed over a period of sixteen or more years”

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong A 3-year project with $ million total funding from ITF and sponsors Project period: June May 2004 Funded by: Major Equipment: Optical Thin Film Coating System Laser Welder Automated Alignment System Polishing System Auto-Stepback Wedge Bonder Precision Die Bonder Wafer scriber Photonic Packaging Laboratory

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Mission: To help build a photonic packaging infrastructure in Hong Kong by: 1.support R&D in industry and academia; 2.technical training; 3.facilitate technology transfer to industry. Technical Team: 13 engineering faculty staff from IE, EE, and ACAE departments, plus 3 full-time technical staff (Dr. Ming Li, April PS Chung, MT Yeung) PI : Hon Tsang, Chester Shu Coordinator: Frank Tong Photonic Packaging Laboratory

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Packaged Components: Lasers, Photodetectors Pigtailed TO-Can photodetector Butterfly FP/DFB laser module AR and HR coated FP Laser Milestone 1 – Fiber attach and basic optical coatings 1 Gb/s Completed 31/7/2002

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong AR coatings (<0.05% reflectivity) on Si and III-V semiconductors HR overlay coatings to enhance reflection and reduce PDL from gold mirrors Milestone 2: High Specification Coatings Completed 28/2/2003 materialt (nm) 8. Ta 2 O SiO Ta 2 O SiO Ta 2 O SiO Ta 2 O SiO Au50 Si sub.

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Milestone 4: Fiber array attachment and MEMS packaging due 30/11/2003 Si optical bench Glass Collimating fiber Si U-grove / V-grove Bonding pads Supporting Si MEMS Output 1 Output 2 Input 2 Input 1

Center for Advanced Research in Photonics Department of Electronic Engineering, The Chinese University of Hong Kong Milestone 5: Multi-component packaging Development of novel self-aligned flip-chip technology for hybrid integration of laser arrays to planar waveguides Collaboration with Institute of Semiconductors, Chinese Academy of Sciences in Beijing on fabrication of compatible FP laser array Collaboration with Shipley on photoresist suitable for 3D topography (needed for patterning metal at bottom of trench due 31/5/2004 waveguide Laser chip Side alignment pedestals Ti/Au/Ti/SiO2 Plated Ni/Au solder Side alignment pedestal Laser die Substrate