Athermalised monolithic VMUX employing silica arrayed waveguide grating multiplexer

The realisation of a monolithic athermalised variable-optical-attenuator-integrated multiplexer (VMUX) implemented in silica-on-silicon waveguide technology is reported. The VMUX incorporates an athermal arrayed waveguide grating, providing <0.05 nm of peak transmission wavelength shift over 20-70/spl deg/C operating ambient independent of attenuator settings.     

High-speed performance of OMCVD grown InAlAs/InGaAs MSMphotodetectors at 1.5 μm and 1.3 μm wavelengths

A report is presented on the fabrication of high-speed In_0.53 Ga_0.47As metal-semiconductor-metal (MSM) photodetectors incorporating a high-quality lattice-matched InAlAs barrier enhancement layer, grown by organometallic chemical vapor deposition (OMCVD). Fast responses of ~55 ps full-width half-maximum at 1.5 μm and ~48 ps at 1.3 μm wavelengths are observed, corresponding to intrinsic device bandwidths of ~8 GHz and ~11 GHz, respectively. The absence of any tail to the pulse response, and of any low-bias DC gain, indicates a low-trap density at the InAlAs/InGaAs heterointerface. Bias independent dark currents of 10-20 μA are observed below breakdown, which occurred at >30 V in devices with a 500-A-thick InAlAs layer     

GaAs/GaAlAs multiquantum well waveguides for all-optical switching at 1.55 mu m

The first measurements of selfphase modulation and nonlinear absorption in a GaAs/GaAlAs multiquantum well (MQW) waveguide near the half-bandgap resonance are reported. An intensity-dependent refractive index coefficient n/sub 2/ of 9*10/sup -14/ cm/sup 2//W and a two-photon absorption coefficient of 0.15 cm/Gw at 1.55 mu m wavelength for TM light were obtained. This corresponds to an intensity-independent figure of merit of 24 rad phase change in one nonlinear absorption length, high enough to allow the implementation of subpicosecond all-optical switches at 1.55 mu m wavelength.<>     

Multistripe array grating integrated cavity (MAGIC) laser: a new semiconductor laser for WDM applications

A novel semiconductor laser formed by monolithically integrating an array of active stripes with a passive planar waveguide bearing an etched-in diffraction grating is reported. Laser emission occurs from different stripes at different, precisely predetermined, wavelengths. It is expected that this laser will find widespread application in wavelength division multiplexed networks.<>     

Monolithic InP-based grating spectrometer for wavelength-division multiplexed systems at 1.5 mu m

A monolithic InP-based grating spectrometer for use in wavelength-division multiplexed systems at 1.5 mu m is reported. The spectrometer uses a single etched reflective focusing diffraction grating and resolves >50 channels at 1 nm spacing with a approximately 0.3 nm channel width and at least 19 dB channel isolation. Operation is essentially of the state of the input polarisation.<>     

Planar lightwave circuit based reconfigurable optical add-drop multiplexer architectures and reusable subsystem module

We describe a wide range of reconfigurable optical add-drop multiplexer architecture designs that may be implemented in standard silica-on-silicon planar lightwave circuits. This proven, reliable technology offers high performance and cost-effective solutions for reducing complex service provisioning in reconfigurable optical networks. Recent advances enable very flexible wavelength routing devices for mesh- and ring-based networks to be implemented on a common subsystem integration platform. We show excellent system performance at 10 Gb/s.     

High-performance InP reflection-grating wavelength multiplexer

A high-performance InP reflection-grating wavelength multiplexer for the 1530-1560 EDFA fibre band is reported. The 8 channel 3.6 nm-spacing devices operated with 30-35 dB channel isolation, <0.04 wavelength precision, and <10 dB on-chip loss. Although realised with 3.6 nm spacings, the multiplexer may be adapted for channels as close as 0.5 nm     

Use of multimode interference couplers to broaden the passband of wavelength-dispersive integrated WDM filters

We describe how multimode interference couplers (MMI) may be used to broaden and flatten the passband of integrated wavelength-dispersive filters. We discuss the approach and demonstrate its effectiveness with a passband-broadened InP arrayed waveguide filter operating at 1.5 /spl mu/m.     

Transit-time limited frequency response of InGaAs MSMphotodetectors

Calculations are reported of the transit-time limited frequency response of InGaAs interdigitated metal-semiconductor-metal (MSM) Schottky barrier photodetectors for 1.55-μm wavelength incident radiation. The response is examined for light which is incident from above and a two-dimensional simulation based on carrier drift is used. It is shown how the impulse response of the device changes as the interdigital spacing and the InGaAs layer thickness vary over the range typically assumed by practical detectors. The device bandwidths are also computed, and the tradeoff which occurs between high-speed performance and high quantum efficiency is studied     

Integrated grating demultiplexer and PIN array for high-density wavelength division multiplexed detection at 1.5 mu m

An integrated wavelength demultiplexer and PIN detector array is reported for high density WDM detection at 1.5 mu m. Signals spaced at 1 nm over the 1.48-1.55 mu m wavelength range are separated and detected; channel passbands are 0.6-0.8 nm. Grown on a semi-insulating substrate, and providing a pseudoplanar device surface, the HD-WDM detector array is suitable for monolithic integration with high-speed multichannel receiver circuitry.<>