J.C. Campbell

Multiplication noise of wide-bandwidth InP/InGaAsP/InGaAs avalanche photodiodes

Measurements of InP/InGaAsP/InGaAs separate absorption, grading, and multiplication avalanche photodiode multiplication indicate that at high gains the excess noise factors approach values predicted by the conventional continuum theory. However, at lower gains the noise is suppressed. This is probably an artifact of the very thin multiplication layers which have been used to increase the gain-bandwidth product. From the frequency response of the noise power, a gain-bandwidth product of 60 GHz, which is consistent with the value of 57 GHz obtained directly from bandwidth measurements, is deduced. >

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes

A theoretical model for the frequency response of InP/InGaAs avalanche photodiodes (APDs) is presented. Included in the analysis are resistive, capacitive, and inductive parasitics, transit-time factors, hole trapping at the heterojunction interfaces, and the avalanche buildup time. The contributions of the primary electrons, primary holes, and secondary electrons to the transit-time-limited response are considered separately. Using a measurement apparatus which consists of a frequency synthesizer and a spectrum analyzer controlled by a microcomputer, the frequency response of InP/InGaAsP/InGaAs APDs grown by chemical-beam epitaxy are measured. Good agreement with the calculated response has been obtained over a wide range of gains. >

High-speed InP/InGaAsP/InGaAs avalanche photodiodes grown by chemical beam epitaxy

High-performance InP/InGaAsP/InGaAs avalanche photodiodes (APDs) grown by chemical beam epitaxy are described. These APDs exhibit low dark current (less than 50 nA at 90% of breakdown), good external quantum efficiency (greater than 90% at a wavelength of 1.3 mu m), and high avalanche gain ( approximately=40). In the low-gain regime, bandwidths as high as 8 GHz have been achieved. At higher gains, a gain-bandwidth-limited response is observed; the gain-bandwidth product is 70 GHz. >

Room‐temperature 1.3‐μm optical time domain reflectometer using a photon counting InGaAs/InP avalanche detector

We demonstrate the first room‐temperature photon counting optical time domain reflectometer at λ=1.3 μm. A high sensitivity (10−14 W) equal to that of a Ge avalanche diode cooled to 77 K has been realized.

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption "grading" and multiplication regions

We have measured the frequency response of InP/ InGaAsP/InGaAs photodiodes with separate absorption, grading, and multiplication regions (SAGM-APDs) for a wide range ( 2 leq M_{0} leq 35 ) of dc gains. The results are explained in terms of a theoretical model which incorporates the transit time of carriers through the depletion region, the RC time constant, the accumulation of holes at the valence band discontinuity of the heterojunction interfaces, and the gain-bandwidth limit.

High-current-gain InGaAs/InP double-heterojunction bipolar transistors grown by metal organic vapor phase epitaxy

By inserting a thin n-InP layer between the p/sup +/-InGaAs base and the n-InP collector excellent transistor characteristics were obtained. The DE and small-signal current gains were 7000 and 11000, respectively, which are the highest values reported for transistors of this type. The transistors were also operated in a collector-up configuration with DE gains as large as 2500.<<ETX>>

An APD/FET optical receiver operating at 8 Gbit/s

A high-sensitivity optical receiver has been designed for a bit rate of 8 Gbit/s and wavelengths of 1.3-1.55mu m. The receiver uses a 60-GHz gain-bandwidth-product InGaAs/InGaAsP/InP avalanche photodiode followed by a high-impedance hybrid GaAs MESFET preamplifier. A bandwidth of 6.9 GHz was measured, with flat frequency response ±2 dB being obtained through the use of a 3-tap transversal equalizer. A sensitivity bar{P} as high as -25.8 dBm was measured for 10-9bit-error rate.

InP/InGaAsP/InGaAs avalanche photodiodes with 70 GHz gain‐bandwidth product

A wide bandwidth (8 GHz) and a high gain‐bandwidth product (70 GHz) have been achieved with InP/InGaAsP/InGaAs avalanche photodiodes (APD’s) grown by chemical beam epitaxy. These APD’s also exhibit low dark current ( 90% at λ=1.3 μm), and high avalanche gain (M0≂40).

Optical AND gate

We have successfully demonstrated a new type of logic circuit which provides an optical output pulse that is the AND function of two wavelength multiplexed optical input signals. The active components of this optically coupled logic gate are a triggerable semiconductor laser and a novel photodetector consisting of two series photodiodes which are sensitive in different wavelength bands.

Avalanche InP/InGaAs heterojunction phototransistor

We report on the characteristics of an avalanche InP/InGaAs heterojunction phototransistor. Below the turnover voltage, the gain is bias dependent and avalanching can be used to achieve significant ( sim5times ) improvement in the gain-bandwidth product. The noise current in this bias region has been measured and is shown to be predominantly shot noise of the photocurrent and the leakage current. Above the turnover voltage, negative resistance is observed and extremely high gains (>104) are achieved. In this mode, the pulse response is a narrow spike (rise time ≃ 20 ns) whose width is independent of the width of the incident optical pulse.