L.W. Stulz

40-wavelength rapidly digitally tunable laser

We present a tunable laser based on an N/sub 1//spl times/N/sub 2/ chirped waveguide grating router that has N/sub 1/N/sub 2/ wavelengths, accessible in a digitally rapid manner, and only N/sub 1/+N/sub 2/+1 semiconductor optical amplifiers. By using chirp, the free-spectral range of the router can be significantly less than the channel span. The version demonstrated here has N/sub 1/=5, N/sub 2/=8, a channel spacing of 100 GHz, and the router free-spectral range is only 20 channels.

Integrated band demultiplexer using waveguide grating routers

We present a novel band demultiplexer design for planar lightwave circuits. It consists of two perfectly sampled waveguide grating routers connected by sets of equal-path-length waveguides separated on one side. Its advantages are compactness, sharp passband corners, and a lack of chromatic dispersion.

Wavelength-division multiplexing cross connect in InP

We demonstrate a 2 line/spl times/2 line, 6 channel/spl times/200 GHz spacing, wavelength-division multiplexing (WDM) cross connect in InP consisting of two interleave chirped waveguide grating routers connected by a series of waveguides with current-controlled phase shifters. Employing a simple fabrication process, we achieved >21-dB extinction ratio, 10-12-dB on-chip loss, and switching currents <17 mA. The present device is, however, polarization sensitive.

16-band integrated dynamic gain equalization filter with less than 2.8-dB insertion loss

We demonstrate a low-loss 16-band dynamic gain equalization filter consisting of two perfectly sampled waveguide grating routers (WGRs) and an array of thermooptic attenuators. This integrated silica waveguide filter has <2.8-dB fiber-to-fiber insertion loss, <0.2-dB polarization-dependent loss at minimum attenuation and <0.7-dB at 10-dB extra attenuation, and <5.0-W electrical power consumption over the C-band. We also demonstrate a new technique for reducing the loss of WGRs.

Integrated WDM dynamic power equalizer with potentially low insertion loss

We present a design concept for dynamically and chromatically variable transmissivity devices for controlling channel powers in wavelength-division-multiplexed systems in which a decrease in attenuation range can be traded for a decrease in insertion loss. We demonstrate a version in InP.

Compact and low-loss manner of waveguide grating router passband flattening and demonstration in a 64-channel blocker/multiplexer

We present a compact design for flattening the passband of a waveguide grating router theoretically without excess loss or chromatic dispersion. We demonstrate its use in a 64-wavelength-channel blocker/multiplexer.

Wavelength selectable laser with inherent wavelength and single-mode stability

We present a 8/spl times/200 GHz wavelength selectable laser that has inherent wavelength and single-longitudinal-mode stability. The wavelength stabilization is accomplished by the long cavity and passive intracavity chirped waveguide grating router, and the single-mode stabilization is accomplished by gain nonlinearities, aided by minimization of cavity length and router passband width.

Polarization diversity waveguide grating receiver with integrated optical preamplifiers

We present an 8/spl times/100 GHz waveguide grating multifrequency receiver in InP with low polarization sensitivity with integrated optical preamplifiers and detectors. The polarization insensitivity is achieved through a special polarization diversity scheme in which both inputs share the same waveguide grating and photodetectors. Also, we show theoretically how chirping the waveguide grating in optically preamplified receivers can improve the sensitivity.

Chirped waveguide grating router multifrequency laser with absolute wavelength control

We apply chirping of the waveguide grating router to the multifrequency laser (MFL). We present a 10/spl times/100 GHz chirped MFL that has precise absolute oscillation wavelength control and guaranteed single router free-spectral-range mode oscillation for all 10 channels and, additionally, guaranteed single cavity mode oscillation for 4 of the channels.

Direct modulation of a multifrequency laser up to 16 x 622 Mb/s

We demonstrate direct modulation results on a 16-channel chirped multifrequency laser without a shared amplifier, There is no optical power penalty compared to the case of a single modulated channel when all 16 channels are modulated simultaneously at 310 Mb/s, and 2 dB power penalty when they all are modulated at 622 Mb/s due to electrical crosstalk. The entire wavelength comb can be shifted by 275 GHz by changing the device temperature from 13/spl deg/C to 33/spl deg/C, while the channel-to-channel power uniformity remains better than 0.2 dB and the optical channel spacing stays exactly 200 GHz.