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A novel traveling-wave electroabsorption modulator (TWEAM) based on undercut-etching-active-region waveguide (UEAW) is proposed and demonstrated. By selectively wet-etching the InGaAsP from InP to reduce InGaAsP active region, the waveguide can reduce parasitic capacitance with high conductivity in n-InP and p-InP cladding layers. In comparison with conventional ridge-waveguide (RW) TWEAM, 3 dB lower optical-insertion-loss, at least 6 dB higher in radio-frequency-link gain (dc to 40 GHz), and faster electrooptical response (3-dB bandwidth of 25 GHz at 50 /spl Omega/-termination for UEAW and 15 GHz for RW) are obtained in UEAW-TWEAM. A 10-Gbs/s operation with low swing voltage of 0.6 V has been achieved in UEAW-TWEAM, a 3.2-dB enhancement over RW-TWEAM. It indicates the tradeoff in designing electroabsorption modulators can be greatly released.

High speeds, high external quantum efficiencies, narrow spectral linewidths, and convenience in coupling make resonant-cavity photodetectors (RECAP's) good candidates for telecommunication applications. In this paper, we present analytical expressions for the design of RECAP's with narrow spectral linewidths and high quantum efficiencies. We also present experimental results on a RECAP having an operating wavelength /spl lambda//sub 0//spl ap/1.3 /spl mu/m with a very narrow spectral response. The absorption takes place in a thin In/sub 0.53/Ga/sub 0.47/As layer placed in an InP cavity. The InP p-i-n structure was wafer bonded to a high-reflectivity GaAs/AlAs quarter-wavelength Bragg reflector. The top mirror consisted of three pairs of a ZnSe/CaF/sub 2/ quarter-wavelength stack (QWS). A spectral linewidth of 1.8 nm was obtained with an external quantum efficiency of 48%. We also demonstrate that the spectral response can be tailored by etching the top layer of the microcavity. The results are found to agree well with those obtained from analytical expressions derived on the assumption of linear-phase Bragg reflectors as well as detailed simulations performed using the transfer matrix method.

Silicon (Si) lasers have long been a goal for semiconductor scientists. A number of important breakthroughs in the past decade have focused attention on Si as a photonic platform. We first briefly study the fundamentals of carrier transition physics in crystalline Si, followed by the most recent progress in the fields of achieving lasing in Si or materials monolithically grown on Si. The hybrid Si platform, a novel III-V-on-Si hybrid integration approach, and the basics of hybrid lasers are then discussed in detail. Advanced hybrid Si lasers based on grating components and ring resonators are reviewed. Several demonstrated photonic integrated circuits on this hybrid Si platform are discussed, showing future possibilities for hybrid Si lasers to be high-performance light sources for Si photonics.

We report the large epitaxial transfer of 100 mm InP/InGaAs/InP wafers to Silicon-on-insulator (SOI) substrates through a low-temperature (300degC) O2 plasma- assisted wafer bonding process. Efficient vertical outgassing channels (VOCs) are developed to eliminate the fundamental obstacle of interfacial voids in bonding due to intrinsic chemical reactions. Generated gas species of H2O and H2 can quickly diffuse to VOCs, etched through-holes to buried oxide layer (BOX), and absorbed by the BOX layer owing to the open network structure and large gas permeability. The interfacial void density is reduced from 55,000 cm-2 down to 3 cm-2, more than five orders of magnitude reduction for appropriate design of VOCs. Uniform patterning of VOCs leads to a no outgassing "dead zone" across the entire bonding area, and decrease of the thermal mismatch-induced interfacial strain potentially as well, which both result in the wafer scale-independent bonding. The bonding strain is observed through X-ray rocking curve measurement conducted on both of a 2 times 2 cm2 bonded pair and 100 mm wafer-scale bonding sample. A variety of devices have been fabricated using this technique. As one example, hybrid silicon evanescent distributed feedback (DFB) lasers integrated with monitor photodiodes have been fabricated using this bonding technique. These highly single mode lasers may find applications in computer interconnects.

High speeds, high external quantum efficiencies, narrow spectral linewidths, and convenience in coupling make resonant-cavity photodetectors (RECAPs) good candidates for telecommunication applications. In this paper, we report a highly-efficient and wavelength-selective separate absorption and multiplication (SAM) avalanche photodiode (APD) with a thin (500 /spl Aring/) absorbing layer. The improved characteristics of the photodetector were obtained by placing the absorption and multiplication layers in a Fabry-Perot cavity. An external quantum efficiency of 77% was achieved with a spectral linewidth of less than 4 nm and an avalanche gain of more than 50. We also present the experimental results on a RECAP having an operating wavelength /spl lambda//sub 0//spl ap/1.3 /spl mu/m with a very narrow spectral response. The absorption takes place in a thin In/sub 0.53/Ga/sub 0.47/As layer placed in an InP cavity. The InP p-i-n structure was wafer bonded to a high-reflectivity GaAs-AlAs quarter-wavelength Bragg reflector. The top mirror consisted of three pairs of a ZnSe-CaF/sub 2/ quarter-wavelength stack (QWS). A spectral linewidth of 1.8 nm was obtained with an external quantum efficiency of 48%.

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.

The effect of three metal conditioners on the apparent bond strength of a single porcelain to four alloys was evaluated. On the basis of the bond strength data the following conclusions can be drawn. The use of metal conditioners provided no improvement in the apparent porcelain-alloy bond strength of Biocast and Biobond alloy. The use of Unibond alloy with its recommended conditioner Uniseal gave lower bond strength values than Unibond without the conditioner. With Rexillium III alloy the use of Uniseal gave the highest bond strength values, but these were statistically equal to those obtained with the recommended coating agent (Jeneric bonding agent). With the exception of Rexillium III alloy, it appears that coating agents may have a function other than bond strength improvement. In light of the continued marketing of new alloys, bonding agents, and porcelains, further research is needed to determine the mechanism of action of bonding agents as well as the porcelain-bonding agent-alloy interaction of various commercial products. Studies designed to address these topics are in progress.

We describe improvements in the structure of the monolithic storage correlator. of improvement open to these devices are bandwidth, storage time, and spurious signal level. We have investigated all of these areas. We have fabricated Sezawa wave Schottky diode correlators. This a llows