M. Makiuchi

Monolithic four-channel photodiode/amplifier receiver array integrated on a GaAs substrate

A four-channel optoelectronic integrated receiver array operating at the wavelength near 850 nm has been fabricated on a single GaAs substrate by using metal-semiconductor-metal (MSM) photodiodes (PDs) and metal-semiconductor field-effect transistors (MESFETs). The largest integration scale for a monolithic receiver and uniform characteristics among circuit channels have been achieved due to the structural simplicity and the process-compatibility of this array. Also, an extremely small capacitance of MSM-PD, 0.10 pF, has lead us to obtain a high-speed operation up to a bit rate of 1.5 Gbit/s, NRZ, and a low noise characteristic exhibiting an equivalent input noise current as small as 5 pA/Hz1/2. These results have indicated the suitability of MSM-PD/MESFETs circuits for large-scale multichannel optoelectronic integration of receivers.

PHYSIOLOGICAL PRODUCTION OF SINGLET MOLECULAR OXYGEN IN THE MYELOPEROXIDASE-H2O2-CHLORIDE SYSTEM

The putative role of singlet oxygen (1O2) in the respiratory burst of neutrophils has remained elusive due to the lack of reliable means to study its quantitative production. To measure 1O2 directly from biological or chemical reactions in the near infrared region, we have developed a highly sensitive detection system which employs two InGaAs/InP pin photodiodes incorporated with a dual charge integrating amplifier circuit. Using this detection system, we detected light emission derived from a myeloperoxidase (MPO)‐mediated reaction in physiological conditions: pH 7.4, 1–30 nM MPO, 10–100 μM H2O2 and 100–130 mM Cl− in place of Br− without the use of deuterium oxide. The MPO‐H2O2‐Cl− system exhibited a single emission peak at 1.27 μm with a spectral distribution identical to that of delta singlet oxygen. Our results suggest physiological production of 1O2 in the MPO‐H2O2‐Cl− system at an intravacuolar neutral pH. The MPO‐mediated generation of 1O2, which may have an important role in host defense mechanisms, is discussed in connection with previous results.

Planar, compatible OEIC's based on multiquantum well structures

An optoelectronic integrated-circuit (OEIC) structure, in which a variety of devices having different functions is built from a common multiquantum-well structure, is discussed. Basic operation of both a lateral-current-injection laser and a field-effect transistor is demonstrated using essentially the same AlGaAs/GaAs multiquantum-well structures.<<ETX>>

A monolithic four-channel photoreceiver integrated on a GaAs substrate using metal-semiconductor-metal photodiodes and FET's

The first fabrication of a monolithic four-channel photoreceiver on a GaAs substrate, using metal-semiconductor-metal (MSM) photodiodes and GaAs metal-semiconductor field-effect transistors (MESFETs) is described. The present photoreceiver operating in the 0.8- µm wavelength region has shown uniform sensitivity with little crosstalk between channels and also giga-bit response. The result suggests that the use of MSM photodiodes and FETs has good expansibility toward high-density and multi-channel monolithic integration.

A monolithically integrated AlGaAs/GaAs p-i-n/FET Photoreceiver by MOCVD

An AlGaAs/GaAs p-i-n photodiode and a GaAs FET have been monolithically integrated on a GaAs substrate by using the metal-organic chemical vapor deposition (MOCVD) technique and by applying a new interconnection technique. A current amplification characteristic consistent to the device parameters has been demonstrated. This result indicates a suitability of MOCVD to realize the monolithic integration of p-i-n/FET photoreceiver.

Efficient fiber coupling to low‐loss diluted multiple quantum well optical waveguides

We demonstrate the use of diluted multiple quantum wells to achieve low‐loss fiber‐matched optical waveguides. A fiber mismatch loss of 0.2 dB/interface and propagation loss of 0.4 dB/cm are achieved at 1.54 μm wavelength using InGaAsP/InP materials.

High-performance, high-reliability InP/GaInAS p-i-n photodiodes and flip-chip integrated receivers for lightwave communications

High-performance, high-reliability InP/GaInAs p-i-n photodiodes have been developed for flip-chip integration. The introduction of ultra-small, planar junctions and microlenses has lead to a high quantum efficiency of 80%, a high-speed response of 21 GHz and a wide fiber alignment tolerance of over 40 mu m. The metallization structure based on an Au-Su/Pt system has been developed and its stability has been confirmed by photodiode aging at 180 degrees C for more than 3000 h. Applicability of flip-chip p-i-n photodiodes has been demonstrated by the fabrication of p-i-n/GaAs amplifier receivers. The minimization of parasitic reactances using flip-chip integration has resulted in a sensitivity of -27.4 dBm at 2 Gb/s, nonreturn-to-zero. These results show the usefulness of flip-chip integration for developing high-performance receivers for lightwave communication systems. >

Low-loss monolithic integration of balanced twin-photodetectors with a 3 dB waveguide coupler for coherent lightwave receivers

Low-loss monolithic integration of a 3-dB waveguide coupler with twin photodetectors using large-mode size guides, mirror coupling, and low-capacitance lateral detectors is demonstrated. Waveguide-mirror integration introduces only approximately=1 dB optical insertion loss at 1.54 mu m wavelength, compared to top-illuminated detectors. Full balanced operation of the monolithic circuit with 33-dB local oscillator intensity noise suppression is demonstrated.<<ETX>>

Integrated waveguide/photodiodes using vertical impedance matching

A novel ‘‘vertical impedance matching’’ approach is demonstrated to improve absorption in evanescently coupled, integrated waveguide/photodiodes by 500% over conventional structures. Our devices exhibit both high absorption at short length (90% at 190 μm) and efficient fiber butt coupling (42%) at 1.3–1.55 μm wavelengths. Unusual transient phenomena are observed in such impedance‐matched devices and discussed theoretically.

GaAs optoelectronic integrated receiver with high-output fast-response characteristics

For obtaining high-output level and high-speed response in a GaAs-based optoelectronic integrated receiver, a circuit involving a two-stage amplifier was first designed and fabricated. A high sensitivity of 400 V/W has been achieved while preserving a high-speed response of 2-Gbit/s nonreturn to zero (NRZ).