Patrick W. Wisk

High performance buried heterostructure 1.55 /spl mu/m wavelength AlGaInAs/InP multiple quantum well lasers grown entirely by MOVPE technique

The fabrication and characterization of a high quality buried heterostructure (BH) type 1.55 /spl mu/m wavelength strained AlGaInAs/InP MQW laser is reported. The lasers have low threshold current density (600 A/cm/sup 2/) for compressively strained MQW measured from a BH chip with cavity lengths of 545 /spl mu/m and 1.5 /spl mu/m wide. Low threshold current of less than 10 mA (2 mA with HR facets coated) is obtained. The differential modal gain of the AlGaInAs devices was also found to be superior to that of the conventional strained GaInAsP system.

Electrical control optical delay lines made of y-junction SOA switches

Electrical control optical delay lines can be made of integrated y-junction SOA switches for many applications. The operation of a cell synchronizer, which can obtain different optical delays, is demonstrated with the fabricated SOA switches.

Characterization of dispersion in higher order mode fibers using electrical spectrum measurements

We present a technique for measuring the chromatic dispersion of the higher order modes in kilometer lengths of fiber. The LP/sub 02/ dispersion is measured for several different fibers, and accuracies better than 1% are achieved.

Wavelength division multiplexed (WDM) data-block switching for parallel computing and interconnects

We report a new generation switch, the data-block switch, which can greatly increase the capacity and reduce the complexity of the interconnect network of a parallel computing system. By using WDM techniques, parallel data can be multiplexed and transmitted through a single fiber. By using photonic switching techniques, we can switch a block of parallel data in one switch operation to any site desired. In this work, we demonstrate such an operation with our fabricated 1 X 2 semiconductor optical amplifier (SOA) switch. This integrated device is an active/passive Y- junction waveguide device with a passive waveguide region in the middle and 3 active waveguide regions at each end. The amplified spontaneous emission spectrum of the SOA shows that this broadband switch can easily cover a wavelength range of more than 64 ITU wavelength grids (100 GHz). The switch operation of multiple wavelengths and the switching speed of the device were studied. A switching time of around 400 ps was achieved.

Integrated coherent transceivers for broadband access networks

We proposed and demonstrated an integrated device with a simple structure that can perform both transmitting and receiving functions with very high receiving sensitivity. The device is composed of a tunable distributed-Bragg-reflector (DBR) laser as a local oscillator (LO) and an integrated detector. An FSK receiver sensitivity of -43.4 dBm at 108 Mb/s was obtained. Multichannel operating characteristics were studied and it was found that systems with an operation channel spacing of 3 GHz can be realized. This device can be operated with either half-duplex or full-duplex mode for broad-band access applications.

Wavelength division multiplexed (WDM) electroabsorption modulated laser fabricated by selective area growth MOVPE techniques

This paper describes the fabrication techniques pertaining to the on-wafer lasing wavelength control of an electroabsorption modulated laser (EML) using both a direct approach and a tunable wavelength source. The direct approach utilizes multiple grating pitches to control the on-wafer lasing wavelength of the DFB arrays. High resolution E-beam lithography was used to generate a phase mask to produce seven grating pitches separated by 0.25 nm pitch intervals. In a tunable wavelength sources approach, we used a multi-electrodes DFB lasers integrated with a bent waveguide for the wavelength tuning. These fabrication techniques show a promising low cost way of mass producing either set of discrete DFB devices with different wavelengths or a more complicated integrated device with wavelength combiner and a modulator.