Avalanche buildup time of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions

The avalanche buildup time of an avalanche photodiode can be determined from the frequency response of the noise power as a function of the dc multiplication M0. In this paper we report on the first measurements of the avalanche buildup time of InP/InGaAsP/ InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions (SAGM-APD's). Measurements on several different device structures reveal that the avalanche buildup time (gain-bandwidth product) decreases (increases) with increasing carrier concentration in the multiplication region. The shortest buildup time that we have observed wasM_{0} times 4.2ps which corresponds to a gain-bandwidth Product of 38 GHz.     

Performance of eight-channel OEIC p-i-n/HBT receiver array in8×2.5 Gb/s WDM transmission system

The performance of an eight-channel, 2.5 Gb/s OEIC photoreceiver array in an eight-wavelength long-distance WDM testbed is described. The sensitivity penalties due to crosstalk and transmission are measured, and the source of crosstalk is investigated. Channel sensitivities range from -25.4 to -26.2 dBm after transmission through 720 km of standard fiber, with transmission penalties ranging from 0.3 dB to 1.0 dB. When the power in each of seven interfering channels is 5 dB above sensitivity, the maximum crosstalk penalty suffered by an individual channel does not exceed 1 dB. These experiments are the first comprehensive characterization of monolithic receiver arrays for crosstalk performance under multichannel operation in a realistic system environment     

Integrated directional couplers with photodetectors by hydridevapour phase epitaxy

The hydride vapour-phase-epitaxial crystal growth technique has been used to realise integrated waveguide-photodetectors and, for the first time, integrated directional coupler-photodetectors for detection in the 1.3 μm to 1.55 μm wavelength range. The GaInAsP waveguides which formed the directional couplers had propagation losses of 2±0.5 dB/cm and more than 90% of the guided light was coupled into the photodetectors. The directional couplers were symmetric with respect to the launch port and had 3 dB coupling lengths of about 1.45 mm     

Dual-channel 1.5 Mb/s lightwave receiver employing an InGaAsP wavelength-demultiplexing detector

A dual-channel 1.5 Mb/s lightwave receiver has been operated simultaneously with optical signals at two different wavelengths. Two individually modulated InGaAsP/InP l.e.d.s provided optical signals at 10 and 1.18 ?m wavelengths, and a new dual-wavelength photodetector served as a demultiplexing detector. The effect of interchannel interference on error rate was measured.     

Improved two-wavelength demultiplexing InGaAsP photodetector

The structure of the previously reported InGaAsP two-wavelength demultiplexing photodetector has been inverted to circumvent fabrication problems associated with dissolution of the lower-bandgap quaternary layer during the LPE growth of subsequent higher bandgap layers. In addition, lower doping levels have been achieved in the LPE layers. The result of these modifications has been devices with greatly improved optical and electrical characteristics. The long-wavelength cutoff has been extended to 1.6 μm.     

Measurement of beam parameters of index-guided and gain-guided single-frequency InGaAsP injection lasers

A value of 1.8 for the astigmatism factor K in narrow stripe InGaAsP/InP lasers is obtained by direct measurement of the beam parameters. Previously, values from 10 to 30 were found for AlGaAs/GaAs lasers of similar geometry.     

Monolithic integrated waveguide photodetector

An InGaAs photodetector for detection in the 1.0?1.5?m wavelength range has been integrated at the end of and above a ridge waveguide in InP. The waveguides were in n?-InP/n+-InP and had an average propagation loss of 3dB/cm at 1.15?m. The reflection losses were 3dB and the coupling loss was 2dB. The photodetector was an InGaAs photoconductor lattice-matched to InP and exhibited a bias-dependent optical gain of up to 2.5 with a unity-gain quantum efficiency of 49% at 1.15?m. 25% of the guided light was absorbed by the photoconductor. The speed of the photoconductor was found to be bias-dependent, varying from 10 ns to 150 ns rise/fall times.     

Highly uniform, high quantum efficiency GaInAsSb/AlGaAsSb double heterostructure lasers emitting at 2.2 mu m

GaInAsSb/AlGaAsSb double heterostructure lasers with low pulsed threshold current density were grown previously by liquid-phase epitaxy using a complicated five-layer structure to relieve the strain arising from graded cladding layers. Double heterostructures have now been grown over a narrow temperature range to minimise this grading. These simpler three-layer DH lasers have high room-temperature quantum efficiencies (5.4% per facet) and low broad-area threshold current densities (2.6 kA/cm/sup 2/) which are uniform from chip to chip.<>     

High-efficiency short-cavity InGaAsP laser with one high-reflectivity mirror

High differential quantum efficiency (70%), high output power (5 mW), and stable single-frequency output at high (1 Gbit/s) modulation rates have been obtained experimentally using short-cavity InGaAsP injection lasers with a metallic mirror on one facet only.     

InGaAsP/InP photodiodes: Microplasma-limited avalanche multiplication at 1-1.3-µm wavelength

Photodiodes for use in the1-1.3-mum wavelength region have been fabricated from double-heterostructure InGaAsP/InP wafers grown by liquid-phase epitaxy (LPE). The measured avalanche multiplication in mesa-configuration devices was limited to values of 10 or less. The results of careful measurement of the photoresponse, quantum efficiency, and reverse-biasI-Vcharacteristics suggest that the gain is limited by microplasma breakdown. The density of microplasmas was estimated to be about 10⁶cm^-2, approximately equal to the etch pit density of the InP substrates used in growth of the epitaxial layers.