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Showing papers on "Photodiode published in 1970"


Journal ArticleDOI
01 Oct 1970
TL;DR: The characteristics of high-sensitivity photodetectors suitable for wide bandwidth optical communication systems are summarized in this paper, where the use of internal current gain by means of avalanche and electron multiplication and optical heterodyne detection is discussed.
Abstract: The characteristics of high-sensitivity photodetectors suitable for wide bandwidth optical communication systems are summarized. Photodiodes, photomultipliers, and photoconductive detectors for wavelengths from 0.3 µm to 10.6 µm are covered. The use of internal current gain by means of avalanche and electron multiplication and by means of optical heterodyne detection to increase sensitivity of high speed photodetectors is discussed. The application to visible and infrared laser communication systems is reviewed.

166 citations


Journal ArticleDOI
TL;DR: In this paper, a photodiode was fabricated using a diffusion technique which formed an n-type surface by stoichiometric adjustment and the electrical and optical properties were measured at 77°K and Dλp∗ values of up to 4 × 109cm Hz12W−1 at 10·6 μm for zero bias resistances of 10 Ω have been obtained.
Abstract: Monocrystalline epitaxial layers of PbxSn1−xTe (0·81 < x < 0·85) have been produced for use as photovoltaic devices capable of radiation detection in the 8–14 μm atmospheric window. The material was grown in an open tube, vapour phase transport system which produced layers of the required composition on lead telluride substrates. The crystalline quality and composition were checked by X-ray and electron diffraction techniques and found to be dependent on the substrate temperature. p-type layers of a reasonable quality, typically 100 μm thick, have been grown on {100} substrates. Photodiodes were fabricated using a diffusion technique which formed an n-type surface by stoichiometric adjustment. The electrical and optical properties of the photodiode were measured at 77°K and Dλp∗ values of up to 4 × 109cm Hz12W−1 at 10·6 μm for zero bias resistances of 10 Ω have been obtained.

37 citations


Journal ArticleDOI
TL;DR: The experimental value of the signal-to-noise ratio (S/N) was used as a criterion for comparing different photomultiplier tubes and for assessing the relative merits of pulse-counting and dc measurement.
Abstract: The experimental value of the signal-to-noise ratio (S/N) was used as a criterion for comparing different photomultiplier tubes and for assessing the relative merits of pulse-counting and dc measurement. For tubes with S-11 and S-20 photocathodes at room temperature, no significant difference was found between pulse-counting and dc methods. When different tubes were compared, other factors being equal, those with smaller cathodes gave higher S/N values. A comparison was also made between a cooled S-1 cathode photomultiplier tube and a p-i-n photodiode at room temperature. The photomultiplier tube was found to have a S/N many times higher than the photodiode.

26 citations


Patent
Paul K Weimer1
22 Jun 1970
TL;DR: In this paper, an image sensor array of photodetector elements, with two phototransistors at each element, has emitter, base, and collector regions, with PN junctions between the regions serving as photodelectors which integrate incident light flux.
Abstract: An image sensor array of photodetector elements, with two phototransistors at each element. Each phototransistor has emitter, base, and collector regions, with PN junctions between the regions serving as photodetectors which integrate incident light flux. The inherent capacitance of the emitter-base junction of one phototransistor is substantially greater than the inherent capacitance of the other junctions, to provide capacitance for charge storage during the period between incident light and sampling. The emitter-base junction of the second phototransistor serves as a switch when the element is sampled, to provide an electrical output representative of the integrated light. The video output may be derived from the collector regions or from either of the emitter regions.

23 citations


Patent
18 Nov 1970
TL;DR: In this paper, a spacecraft solar cell system including a switching circuit which comprises relay operated switches for changing a plurality of solar cells from a first series-parallel interconnection to a second series parallel interconnection is disclosed.
Abstract: A spacecraft solar cell system including a switching circuit which comprises relay operated switches for changing a plurality of solar cells from a first series-parallel interconnection to a second series-parallel interconnection is disclosed. The relays are actuated by a command device which may be a telemetry receiver. A protection circuit comprising a photodiode is connected between the command device and the relays to ensure appropriate solar cell orientation when switching occurs. This prevents arcing across the relay switches.

20 citations


Journal ArticleDOI
TL;DR: A new germanium photodiode having an extremely uniform quantum efficiency from the visible to 1.65 micro has been developed, and can be background limited by 300-K blackbody radiation.
Abstract: A new germanium photodiode having an extremely uniform quantum efficiency from the visible to 1.65 μ has been developed. The device consists of a lithium-drifted junction in which the light enters in a direction parallel to the junction, thereby allowing absorption path lengths of several centimeters, if desired, with essentially zero dead layer. Sensitive areas up to about 10 mm in one dimension and several centimeters in the other dimension are possible. Typical characteristics for a device 2 cm long having a sensitive area 7 mm × 7 mm are: diode capacitance, 3 pF; charge collection time, 75% of charge collected in 25 nsec at 500 V; measured NEP, 3.7 × 10−15WHz−12 at 1.625 μm and 77 K for frequencies up to 30 kHz, and 5.5 × 10−13WHz−12 at 1.625 μm and 195 K for frequencies up to 40 kHz. At low frequencies, the detectivity can be background limited by 300-K blackbody radiation. The device must be used and stored at reduced temperatures. A convenient cryostat, capable of maintaining the device at or near 77 K for 150 h without refilling, is described.

20 citations


Patent
20 Mar 1970
TL;DR: In this paper, a signal processing circuit employing an array of photodetector elements, with each element including a phototransistor having a capacitor coupled to the base region, is described.
Abstract: A signal processing circuit employing an array of photodetector elements, with each element including a phototransistor having a capacitor coupled to the base region. The base-collector junction integrates incident light flux in response to an electromagnetic input, while the emitter-base diode serves as a switch when the element is sampled, to provide an electric output representative of the integrated light. The capacitor provides charge storage during the period between light flux integration and sampling.

18 citations


Journal ArticleDOI
TL;DR: The technique of measuring the power ratio by irradiating a smoked or painted target of known diffuse reflectance at a fixed range is used to calibrate a complete lidar system.
Abstract: In order to obtain quantitative data on the backscatter function from laser irradiance backscattered from the atmosphere, the ratio of power transmitted to power received must be accurately known. No absolute measurements of power, optical system transmittance, detector quantum efficiency, or electronic gain are necessarily required. The technique of measuring the power ratio by irradiating a smoked or painted target of known diffuse reflectance at a fixed range is used to calibrate a complete lidar system. The relative area of the output power pulse is monitored by a fast response photodiode, and the relative area of the returned pulse is also recorded after passing through a filter of known high optical density. It is essential to control the temperatures of the laser rod and receiver interference prefilter to ensure proper spectral matching. Field experience gained using this technique is described, and examples of calibration measurements and backscatter functions for smog and cirrus clouds are presented.

16 citations


Journal ArticleDOI
TL;DR: In this article, the performance of position-sensitive Schottky barrier gold-silicon photodiodes in the presence of uniform radiant background levels is investigated, and proper conditions of reverse bias and external circuit loading are shown to reduce the background saturation effects while maintaining nearly constant responsivity.
Abstract: Performance of position-sensitive Schottky barrier gold-silicon photodiodes in the presence of uniform radiant background levels is investigated. Proper conditions of reverse bias and external circuit loading are shown to reduce the background saturation effects while maintaining nearly constant responsivity. The response of the lateral photovoltaic photodetector to CW-modulated and short pulse-width light signals is described. The effect of signal time dependence on the lateral falloff parameter is considered.

13 citations


Patent
13 Feb 1970
TL;DR: In this article, an optical positive feedback sensor circuit which converts regularly coded information into electrical signals is presented, and a circuit is included to maintain a light level at least sufficient to restart the operation after a period of light obstruction.
Abstract: An optical positive feedback sensor circuit which converts regularly coded information into electrical signals. When not obstructed by the coded opaque pattern on a moving information carrier light from a light emitting diode is detected by a phototransistor. The output of the phototransistor is then amplified. A portion of the amplifier output provides positive feedback through the light emitting diode, driving the circuit into saturation. A circuit is included to maintain a light level at least sufficient to restart the operation after a period of light obstruction.

12 citations


Patent
Arthur C M Chen1
31 Aug 1970
TL;DR: In this paper, a diode read only memory array is described, in which the intersecting signal lines of the array are connected by a series circuit comprising a conventional diode and a photodiode, oppositely poled.
Abstract: A diode read only memory array is disclosed in which the intersecting signal lines of the array are connected by a series circuit comprising a conventional diode and a photodiode, oppositely poled. Information is stored by selectively irradiating the array to produce reverse conduction in selected ones of the photodiodes. The integrated circuit structure used in fabricating the memory array is also disclosed.

Journal ArticleDOI
01 May 1970
TL;DR: In this article, the light-receiving area of an avalanche photodiode has been enlarged by means of a tapered light-focusing fiber guide, which can enlarge the light receiving area.
Abstract: The light-receiving area of an avalanche photodiode has been effectively enlarged by means of a tapered light-focusing fiber guide.

Journal ArticleDOI
TL;DR: In this article, a local oscillator was applied to an avalanche photodiode to perform both optical and electronic mixing in an optical heterodyne receiver, and experiments showed that very low conversion losses are possible.
Abstract: Application of a local oscillator to an avalanche photodiode enables it to be used as an electronic mixer when demodulating optical signals varying in amplitude. In an optical heterodyne receiver the diode performs both optical and electronic mixing. Experiments are described which show that very low conversion losses are possible. The method has significant advantages over more conventional techniques.

Journal ArticleDOI
TL;DR: In this paper, the authors used a direct current to 5 GHz real-time oscilloscope to display 100 ps full width at half maximum (FWHM) pulses on a photodiode.
Abstract: Pulses of 100 ps full width at half maximum (FWHM) have been displayed on a direct current to 5-GHz real-time oscilloscope. The 100-ps duration includes contributions from the oscilloscope, the photodetector, and the laser pulse,Maximum current in the linear regime of the photodiode is ≈3 amperes so that electric pulses of ≈70 ps FWHM and ≈150 volts can be obtained with the laser-detector combination. Results of a simple optical method for determining the exposure time of high-speed electronic cameras are also briefly given.

Journal ArticleDOI
01 Feb 1970
TL;DR: In this paper, a self-scanned image sensor consisting of a linear integrated-circuit array of photodiodes and metal-oxide-semiconductor (MOS) transistors was studied.
Abstract: Studies were carried out on a self-scanned image sensor comprising a linear integrated-circuit array of photodiodes and metal-oxide-semiconductor (MOS) transistors. It was found that the maximum scanning rate is about 2.5×105bits/s, and that the value is mainly restricted by the photo-induced current and the junction capacitance of the photodiode.

Journal ArticleDOI
W. M. Sharpless1
TL;DR: The method uses a single laser beam modulated at a high frequency, 4 GHz, to simulate the signal and local oscillator in a conventional optical receiver thus avoiding the problem of aligning two separate optical beams; the results obtained can be applied to the design of an optical heterodyne receiving system.
Abstract: This paper describes a method of evaluating the high frequency signal and noise performance of photodiodes suitable for mixers in an optical heterodyne receiver. The method uses a single laser beam modulated at a high frequency, 4 GHz, to simulate the signal and local oscillator in a conventional optical receiver thus avoiding the problem of aligning two separate optical beams; the results obtained can be applied to the design of an optical heterodyne receiving system. A new Schottky-barrier gallium arsenide photodiode is described, and measurements of a typical diode of this type are used as an example for comparison with theory. The photodiodes employed are of the same basic gold-dot epitaxial gallium arsenide type that has previously been used for millimeter wave and microwave mixers, but they have been modified to allow for the introduction of an optical beam from beneath the gold-dot contact area. A typical diode has a barrier capacitance of 0.027 pF, a series resistance of 30 Ω, and an effective quantum efficiency of 40%, which could be improved to perhaps 60% by an antireflection coating on the photodiode surface.

Patent
19 Oct 1970
TL;DR: In this paper, the reverse bias potential is applied to the sources as well as the drains of the two transistors to render them nonconductive and to charge both photodiodes to the same reverse bias bias potential.
Abstract: An optically settable memory cell includes two MOS transistors each having a gate cross-coupled to the drain of the other transistor to provide a bistable circuit. Each transistor has a drain extending over an area of the substrate to form a photodiode. Bias potential is applied to the sources as well as the drains of the two transistors to render them nonconductive and to charge both photodiodes to the same reverse bias potential. The application of potential to the drains is interrupted while a differential input light signal is applied to the photodiodes to cause an unequal discharging of the photodiodes. Potential is then removed from the sources and restored to the drains, whereby the transistor having its gate connected to the photodiode having the greater charge is rendered conductive, and the transistors then store an optically determined information bit.

Patent
09 Dec 1970
TL;DR: In this article, the dimensions of a P + PNN + photosensitive device are selected so that when reverse biased at its reverse breakdown voltage the depletion layers nearly fill the P and N type regions.
Abstract: 1,215,557. Semi-conductor devices. NIPPON ELECTRIC CO. Ltd. 30 July, 1969 [30 July, 1968], No. 38294/69. Heading H1K. The dimensions of a P + PNN + photosensitive device are selected so that when reverse biased at its reverse breakdown voltage the depletion layers nearly fill the P and N type regions. As shown, Fig. 2, an avalanche-type photodiode comprises an N type epitaxial layer 3 doped with As grown on an N type Si substrate 4, and having a P type layer 2 and a P + type layer 1 formed by diffusion of Ga and B respectively. The P and N type regions have relatively low impurity concentrations so that a junction with a low impurity concentration gradient is obtained. The device has uniform avalanche properties over the junction area without reduction of the internal quantum efficiency or increase in the spreading resistance. Design equations are given. The semi-conductor material may also be Ge, GaAs, GaP, or InSb.


Journal ArticleDOI
01 Oct 1970
TL;DR: In this paper, a reverse-biased HgCdTe photodiode was used for heterodyne detection at 10.6 µm in a reversebiased HGcdTe this paper.
Abstract: Expressions are given for heterodyne noise equivalent power, conversion gain, and frequency response in terms of diode parameters, local oscillator power, and IF amplifier noise factor. Experimental results are reported on heterodyne detection at 10.6 µm in a reverse-biased HgCdTe photodiode.

Journal ArticleDOI
TL;DR: In this paper, a novel optical probe is used as the sensor of an automatic hydraulic model contour follower, which consists of a light source, a split lightpipe, and a photodiode.
Abstract: A novel optical probe is used as the sensor of an automatic hydraulic model contour follower. The sensor consists of a light source, a split lightpipe, and a photodiode. With an electromechanical servo system the probe is kept at a fixed, small distance from the contour to be measured. As the servo driven probe assembly is moved across the model to be measured, output signals proportional to the horizontal and vertical displacements are fed into an X-Y plotter, thus producing a profile of the model. The accuracy is better than 1/32″ (0.80101).

Patent
13 Jan 1970
TL;DR: The control input for the regulator is derived from the number and/or intensity of electrical flash overs which are detected optically as in DT P1276001 as mentioned in this paper, where any flash over whose duration is at least one order less than the pulse length of the rectified voltage or current pulse in which it occurs, is converted in the high voltage circuit into an optical signal which in turn is detected directly or over optical wave guide by a photoelectric cell in the regulator circuit.
Abstract: The control input for the regulator is derived from the number and/or intensity of electrical flash overs which are detected optically as in DT P1276001. Any flash over whose duration is at least one order less than the pulse length of the rectified voltage or current pulse in which it occurs, is converted in the high voltage circuit into an optical signal which in turn is detected directly or over optical wave guide by a photoelectric cell in the regulator circuit. The original optical signal is either from a photo diode (gallium arsenide or phosphide) in parallel with a resistor in the high voltage supply and whose volts drop varies with transients due to flash over or by a Kerr cell in a monochromatic polarized light beam falling directly or via light guide on the photocell, the Kerr cell is connected across the top of a potential divider chain.

Patent
04 May 1970
TL;DR: In this paper, a photoresponsive device employing a silicon photocell to excite on illumination of the photocell a transistor in a discriminator circuit and drive the transistor from a nonconducting to a conducting condition.
Abstract: A photoresponsive device employing a silicon photocell to excite on illumination of the photocell a transistor in a discriminator circuit and drive the transistor from a non-conducting to a conducting condition. The photovoltaic output of the silicon cell is added to the potential of the direct current potential of a bias source to exceed the threshold conduction potential of the discriminator transistor. Thermostability is achieved by employing a transistor in the bias source of identical type and similar characteristics to the discriminator transistor. The discriminator transistor has an emitter-collector circuit which includes a load resistor, and the output which is developed across the load resistor is amplified by a common emitter transistor amplifier circuit. The transistor of the amplifier circuit is a N-P-N, while the transistor of the discriminator circuit is a P-N-P type. A switching transistor is used in the common emitter circuit of the discriminator transistor. In the optical encoder disclosed, a separate discriminator circuit is employed for each silicon photodiode, but a single direct current bias source is employed. The switching transistors are pulsed, either sequentially or at the same time to interrogate the photodiodes.

Journal ArticleDOI
TL;DR: In this paper, a constant false alarm rate closed loop is used to control photodiode bias over varying operating conditions such as temperature or ambient illumination and changes in photode parameters.
Abstract: A constant false alarm rate closed loop controls avalanche photodiode bias over varying operating conditions such as temperature or ambient illumination and changes in photodiode parameters. The photodiode output is amplified, sensed in a threshold circuit, shaped to a constant amplitude and duration, and integrated. The integrator, also fed by a constant current representing the desired false alarm rate, generates an output proportional to the integrated error in false alarm rate. This control signal alters the photodiode bias until the integrated false alarm rate error is zero.

Journal ArticleDOI
C.A. Burrus1, W.M. Sharpless1
TL;DR: In this paper, a near-planar diffused p-n junction germanium photodiode has been fabricated for use at an optical wavelength near 1 μm, and its performance as a demodulator at microwave frequencies is discussed.
Abstract: A small-area (∼ 5 × 10 −7 cm 2 ), near-planar, diffused p - n junction germanium photodiode has been fabricated for use at an optical wavelength near 1 μm. The fabrication of the diode is described, and its performance as a demodulator at microwave frequencies is discussed. The diode was evaluated at an optical wavelength of 1.15 μm and a modulation frequency of 4.18 GHz, where the detected signal power and the shot-noise power were measured. For an optical power input of 0.8 mW, an intensity modulation index of 0.24 and an effective bandwidth of 3 MHz, the signal-to-shot-noise ratio at the optimum bias point was about 64 dB.

Patent
08 Jan 1970
TL;DR: In this article, a two-dimensional photodiode array including insulating-gate field effect transistor switching elements for the photodiodes is described, operating in the photon flux integration mode.
Abstract: A two-dimensional photodiode array including insulating-gate field-effect transistor switching elements for the photodiodes is described. The photodiodes operate in the photon flux integration mode and means are provided for sequentially scanning the photodiodes in the array. The array is fabricated by metal oxide semiconductor (MOS) techniques or by the more preferred silicon gate fabrication method.

Journal ArticleDOI
W.A. Gambling1, P.J.R. Laybourn1, M.D. Lee1, H.R.D. Sunak1, M. Anson1 
TL;DR: In this article, two simple methods are described for accurately tuning a mode-locking device for a laser, one is suitable for an acoustic diffraction cell and involves a simple measurement of the diffracted light.
Abstract: Two simple methods are described for accurately tuning a mode-locking device for a laser. The first is suitable for an acoustic diffraction cell and involves a simple measurement of the diffracted light. The second can be used with any type of active mode locking and requires only a photodiode and a simple low-frequency spectrum analyser.

Book ChapterDOI
01 Jan 1970
TL;DR: In this article, the authors considered the photovoltaic effect when a semiconductor body containing a p-n junction is exposed to optical illumination, where one ohmic contact is on the p-region of the body and the second one on the n-region, and both contacts are on the same type of material.
Abstract: The photovoltaic effect is the generation of a voltage due to optical excitations when a semiconductor is illuminated at the electrodes or at internal barriers or p-n junctions. The specific effect that will be the subject of these lectures is the voltage developed when a semiconductor body containing a p-n junction is exposed to optical illumination. Two possibilities exist and both will be considered; one, when one ohmic contact is on the p-region and the second ohmic contact is on the n-region of the body; and two, when both contacts are on the same type of material. These are known as the transverse photovoltaic effect and the lateral photovoltaic effect, respectively. These are designated in Figure 1. The transverse photovoltaic effect is commonly used in solar energy converters, photodiodes, radiation detectors, special types of null detectors and tracking detectors, etc. The lateral photovoltaic effect is used at present only in what is commercially known as the radiation tracking transducer. For most applications, the devices are operated in the steady state condition with the radiation continuously falling on the devices (or with the radiation intensity changing slowly compared to the time constants of the device). Thus most of the discussion will be devoted to the steady state solutions of the fundamental relations.

Patent
13 Jul 1970
TL;DR: In this article, a photo detector bias control is applied to the photo detector in accordance with the rate of pulses exceeding a threshold level, the latter being determined by a comparison of the pulse integration with a reference voltage after the pulses have been shaped in a mono-stable multivibrator.
Abstract: 1279349 Photo detector bias control HUGHES AIRCRAFT CO. 13 July 1970 [22 July 1969] 33903/70 Heading G1A In a detector system using a photo multiplier or photo diode of the avalanche type for ranging i.e. measuring distances, the rate of response to non signal inputs is maintained substantially constant by controlling a bias applied to the photo detector in accordance with the rate of pulses exceeding a threshold level, the latter being determined by a comparison of the pulse integration with a reference voltage after the pulses have been shaped in a mono-stable multivibrator. The circuit may have separate thresholds for the output path and the bias control path. The potential sit point 13 Fig. 1 in the supply line to avalanche diode 10 is controlled by the output from an integrater 22 which output is a function of the difference of effect of the shaped pulse from MV20 and a reference source 24. A shaped pulse from the MV is indicated by an excursion of the input above the threshold, and the duration of a shaped pulse is in excess of a ranging period when used in a radar system. Excursions are ineffective during a pulse.

01 Nov 1970
TL;DR: In this paper, high speed (Hg,Cd)Te photodiode detectors sensitive to 10.6 microns radiation with operating temperature range of 77 to 90 K were presented.
Abstract: High speed (Hg,Cd)Te photodiode detectors sensitive to 10.6 microns radiation with operating temperature range of 77 to 90 K