A theory based on the Boltzmann equation is used to study rectification by Schottky barriers at frequencies as high as infrared. This theory is concerned only with effects originating inside the space‐charge region, the voltages across this region being regarded as given. Thus, we confine our attention to transport mechanisms and exclude what are known as ’’circuit effects.’’ Typically, it is found that rectification is nearly constant from zero frequency to the plasma frequency of the bulk semiconductor, then drops as ω−2. A reversal of the sign of the rectification current is predicted near ωp. The small‐signal impedance of the junction is calculated as a function of frequency. The theory is extended to mixing of two weak signals, and mixer output is calculated as a function of beat frequency. It is found that this output can be much larger than the value one would estimate from the ideal‐diode equation.

Transport theory of high-frequency rectification in Schottky barriers

Pulsed microwave radiation in a tuning range from 10 to 30 GHz has been generated through the parametric interaction of two near-infrared pulses in GaP crystals at low temperatures. The power of the microwave pulses (duration 30 nsec) was of the order of 1 mW. The pump pulses were generated with a Nd:YAG laser emitting simultaneously at two frequencies, within the bandwidth of the 1.064-microm transition, as a result of an etalon output coupler.

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Generation of tunable pulsed microwave radiation by nonlinear interaction of Nd:YAG laser radiation in GaP crystals.

A transmission experiment through a free-space laser transmission simulator for an optical intersatellite link is proposed and demonstrated For multigigabit optical intensity modulation, adoption ofboth a direct current modulation of the laser diode and external optical intensity modulator are examinedBit error rate (BER) characteristics, including the far-field pattern (FFP) of the optical antenna and beamcoupling loss, as well as beam pointing error fluctuation are clarified in assuming intersatellite distancesDesign directions of the optical beam tracking system and high capacity optical transmission in the 083tm wavelength region, between optical intersatellite links, are clarified in this experiment 1 INTRODUCTION An optical intersatellite link (ISL) can enable a small satellite to handle a large number of transmis-sions, to support human activity on earth as well as in space For example, optical ISLs between low-earthorbit (LEO) satellites can become the infrastructure for mobile and personal communications on a globalscale[fl It might be no exaggeration to say that, sooner or later, a multigigabit data highway through theuniverse will be requiredATR has been developing a transmitter[2I and a receiver as well as an optical antenna[31 for anoptical ISL At the final stage of development, transmission tests that include these overall elements mustbe conducted under conditions that are as realistic as possibleThis paper focuses on a transmission experiment in our free space laser transmission simulator[4I,using a transmitter and receiver designed for gigabit use, and an optical antenna Many transmission ex-periments for optical ISLs have been reported[5I, however, to our best knowledge, no transmission experi-

Multigigabit optical transmission experiment through a free-space simulator

Laser resonator losses with output coupling apertures (holes) have been calculated before but in limited ranges. We have extended such calculations, for the benefit of laser designers, using full diffraction theory, to cover the range of the Fresnel Number N up to 100. Here N is defined by a2/λb with a the radius of the two mirrors and b their separation, while λ is the wavelength of interest. The losses have been examined from the point of view of the field configuration at the mirrors. Such field is modified, in turn, by the size of the aperture.

Losses of Aperture Coupling Resonators for Extended Range of Fresnel Numbers

In this work we report a complete theory of the metal-insulator-metal, antenna coupled, mm and sub-mm detectors. The voltage-power responsivity is simply derived from the geometrical antenna proprieties and the electrical junction characteristics. The calculated responsivity simply foresees our experimental results in the sub-mm — mm range and well fits all the previously reported data

Theoretical and experimental responsivity of fir antenna coupled metal-insulator-metal detectors

A detailed experimental study of the low frequency (video) response of a quasioptical Schottky diode detector over the microwave and FIR wavelength range is presented. An optimization of the responsivity versus the bias current is proposed and a generalized curve of the saturation power versus the FIR wavelength is given. This curve defines for any antenna point-contact Schottky diode detector, suitable for FIR detection, the power range for a linear detector response. A simple method is also described to calculate the coupling efficiency of the laser radiation into the antenna reception pattern.

Low frequency characteristics of a quasioptical Schottky diode detector part II: Experimental results

Heterodyne investigations into FIR laser outputs and quasi-optical Schottky barrier diode detectors

A heterodyne 840-nm laser diode system operating up to 1 Gbit/s has been studied in detail with respect of its potential use for intersatellite link (ISL) communication. The breadboard uses only commercially available components and is designed to operate with single filter FSK or CPFSK demodulation scheme. The system sensitivity has been measured for 1 Gbit/s pseudorandom patterns and has been compared with direct detection results from the same test bed. The overall breadboard performances are discussed with respect to ISL communication requirements.

Study of a 1-Gbit 0.84-um heterodyne system for ISL application

A detailed theoretical and experimental study of the heterodyne performance of a quasioptical Schottky diode detector is presented The experimental results have been obtained by mixing the radiation from a FIR laser with the output of a 67–73 GHz Klystron The heterodyne signal variation versus various parameters and its relation to the special case of two lasers mixing are described The mixer characteristics are a NEP value of 2×10−19W/Hz and a detector bandwidth of at least 9 GHz Experimental evidence of harmonics generation of submillimetric frequencies at the diode junction is also presented

Heterodyne performance of a quasioptical Schottky diode detector: Theoretical and experimental results

This paper summarizes theoretical work that was performed at MPB Technologies Inc. to explain the behaviour of a certain type of non-linear detector. A theoretical model of the rectifying mechanism taking place at the Schottky junction of a quasioptical Schottky diode detector has been developed and compared to various experiments of FIR and microwave detection. An excellent fit has been obtained between this model and the experimental results for both video and heterodyne detection. This study has resulted in a good understanding of the detector behaviour. The existence of an optimum diode biasing current has been shown. A generalized theoretical curve of the saturation power has been calculated for the complete SMM wavelength range. This curve defines the linear dynamic range of any type of Schottky diode detector device. The theory has been also extended to higher order terms to describe the non-linear effects observed at high biasing currents and for strong incident radiation.

A. Waksberg

Papers

Low frequency characteristics of a quasioptical Schottky diode detector part II: Experimental results

Heterodyne investigations into FIR laser outputs and quasi-optical Schottky barrier diode detectors

Study of a 1-Gbit 0.84-um heterodyne system for ISL application

Heterodyne performance of a quasioptical Schottky diode detector: Theoretical and experimental results

Schottky Diode Detector Research At MPB Technologies Inc.