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A nonblocking photonic switch can be used to implement a tapped delay line with a large number of adaptive weights and a wide range of time delays. An advantage of using optical tapped delay lines for adaptive filtering is that the operating frequency can be quite high, in the 10-100 GHz range. We present a sparse reconfigurable adaptive filter (SRAF) based on a photonic switch with an input/output connection architecture that can be represented by a matrix of adaptive weights. This unique parallel structure can be reconfigured in an adaptive manner to implement a sparse filter impulse response for use in many applications. We consider an adaptive algorithm for this filter that chooses the input and output delays using a cross-correlation-based approach and connects these delays by weights that are adapted using a gradient algorithm. An alternative adaptive algorithm is also considered that is based on a system identification formulation where the weights are first adapted, and then the appropriate delay combinations are chosen. A search algorithm for implementing the connection constraint required by the SRAF is also discussed whereby each input is connected to only one output at any moment. Computer simulation examples are presented to illustrate the behavior of the filter for a system identification model.

We describe the design and performance of a number of elements based on traveling-wave electroabsorption modulators (TW-EAMs) in optical time-division-multiplexing (OTDM) and wavelength-division-multiplexing (WDM) networks. The incorporation of traveling-wave (TW) electrode design into electroabsorption modulators (EAMs) relieves the resistance-capacitance (RC ) bandwidth limitation common to lumped components, enabling higher operation speed without shortening the device. As a result, high-speed operation can be combined with essential modulator characteristics such as modulation efficiency and extinction ratio. While significant modulation bandwidth has been achieved, a lesser known aspect is that the TW electrode also provides an extra dimension for improving and enabling functionalities beyond broadband modulation. This new dimension originates from the distributed effect of the TW design and its interactions with distinctive EAM properties. This paper reviews such developments in recent years with specific applications for optical signal processing in OTDM and WDM networks. The covered functionalities include various optical gating operations for OTDM, regenerative wavelength conversions for WDM, and clock recovery

The first monolithically integrated attenuated counter-propagating optical phase-locked loop based coherent receiver is presented. A spurious-free dynamic range of 131.3 dB Hz 2/3 is measured in the detector shot-noise limit at 100 MHz, which is the highest reported for a single-chip device.

TBA and TBP are liquid organometallic sources that are a safer alternative to arsine and phosphine. Using TBA and TBP, we have successfully grown lattice matched In0.53Ga0.47As/InP single quantum well lasers emitting at 1.5 μm with a threshold current density of 220 A/cm2 for broad area devices 3.5 mm in length.

Hg 1-x Cd x Te has been grown on CdTe substrates by liquid-phase epitaxy (LPE) from: 1) Te-rich solution at atmospheric pressure in a slider system, 2) Hg-rich solution in a sealed tube dipping system, and 3) HgTe-rich solution in sealed tube tipping and sliding systems. For epitaxial layers grown from Te-rich solution at 500°C, the width of the graded composition region is 3 µm and the compositional variation across the layer and with depth into the layers is less than ±0.01 mole fraction CdTe. The graded composition region for layers grown from Hg-rich solution at 460°C is less than 3 µm; however, there is no uniform composition region because of CdTe depletion from the melt. The graded bandgap region for pseudobinary growth at 700°C is much wider (20 µm) than the other two cases; however, a region of uniform composition can be obtained by growing sufficiently thick layers (> 30 µm). Pseudobinary growth has the theoretical advantage that either p-type or n-type layers may be grown, whereas, only p-type layers may be grown from Te-rich solution at atmospheric pressure.

Harmonic and intermodulation distortion are two crucial performance parameters of laser diodes in determining their utility in wide-bandwidth analog links. The multimode rate equations are solved numerically to give information on the bandwidth phase, harmonic, and intermodulation distortion of GaInAsP laser diodes at both small- and large-signal levels. The results of the theoretical analysis agree well with experimental results, and show that the effects of both spatial and spectral hole burning are necessary to create an accurate theoretical model that correctly predicts the modulation damping and distortion levels for a range of lateral cavity structures. Anomalous variations in the low-frequency harmonic and intermodulation curves at high modulation levels are explained with this model. The model can be used for any arbitrary input current waveform, and provides information on the output optical spectra which can be used to analyze the propagation of the waveform along an optical fiber. >