Optoelectronic amplifier

Claim 2

An optoelectronic amplifier comprising: a negative resistance element having a peak and a valley in its voltage-current characteristic; a DC power source for supplying electric power to said negative resistance element; a light-emissive element for operatively generating output light when a voltage applied thereacross exceeds a threshold value, said light-emissive element being connected in series with said negative resistance element and said DC power source so as to be biased forwardly by said DC power source, said negative resistance element being operated at a stable operation point near said valley by a forward resistance of said light-emissive element; and a photoelectric conversion element connected in parallel across said negative resistance element so as to be biased reversely by said DC power source via said light-emissive element form said DC power source is divided to flow through said photoelectric conversion element and said negative resistance element parallely, said photoelectric conversion element having a high reverse resistance when no input light is applied thereto, which resistance is reducible when an input light is applied, said forward current flowing through said lightemissive element being so determined that a voltage produced across the light-emissive element is smaller than the threshold value when no input light is applied, while it is larger than the threshold value when an input light is applied, whereby output light is obtained only when and input light is applied to said photoelectric conversion element.

Claim 3

An optoelectronic amplifier comprising: a negative resistance element having a first low-voltage high-current state and a second high-voltage low-current state; an electric power source; load means including a light-emissive element connected in series with said power source and said negative resistance element, so that said light-emissive element is forwardly biased by said power source via said negative resistance element, said load means functioning as a load for said negative resistance element so as to normally operate said negative resistance element at said first state; and control means including a photoelectric conversion element which operatively reduces its conductivity when applied thereto with input light, said control means being connected in parallel across said negative resistance element for operatively switching said negative resistance element from its first state to said second state in response to the reception of input light, said light-emissive element operatively emitting output light when said negative resistance element is in said second state, whereby said light-emissive element is switched into its light-emissive condition when an input signal is applied to said control means.

Claim 4

An optoelectronic amplifier comprising: a negative resistance element having a first low-voltage high-current state and a second high-voltage low-current state; an electric power source; load means including a light-emissive element connected in series with said power source and said negative resistance element, so that said light-emissive element is forwardly biased by said power source via said negative resistance element, said load means functioning as a load for said negative resistance element so as to normally operate said negative resistance element at said first state; and control means including a photoelectric conversion element which operatively reduces its conductivity when applied thereto with input light, said control means being connected in parallel across said negative resistance element for operatively switching said negative resistance element from its first state to said second state in response to the reception of input light, said light-emissive element operatively emitting output light when said negative resistance element is in said second state, whereby said light-emissive element is switched into its light-emissive condition when an input signal is applied to said control means.

Claim 5

The optoelectronic amplifier according to claim 2, wherein said photoelectric conversion element is a photodiode connected across said negative resistance element so as to be reversely biased by said power source via the forwardly biased light-emissive element, whereby the reverse resistancE of said photodiode is reduced when input light is applied thereto.

Claim 6

The optoelectronic amplifier according to claim 2, wherein said photoelectric conversion element is a photoconductive element and said control means further includes bias means connected in series with said photoconductive element, said series circuit of the photoconductive element and the bias means being connected in parallel across said negative resistance element so that the negative resistance element is reversely biased by said biased means through said photoconductive element whose resistance is reduced when input light is applied thereto.

Claim 7

The optoelectronic amplifier according to claim 2, wherein said photoelectric conversion element is a phototransistor connected at the collector and the emitter thereof across the negative resistance element and said control means further includes bias means connected to the base of said phototransistor for supplying a control bias to the phototransistor so as to allow an increase of current to flow therethrough in response to the reception of input light.

Claim 8

The optoelectronic amplifier according to claim 2, wherein said negative resistance element has a high-voltage low-current stable operation point which is determined by a resistance of said load means, the voltage-current characteristic of said negative resistance element and the magnitude of said power source, said negative resistance element having its operation state changed from the stable operation point to a different unstable operation point when light is applied to said control means.

Claim 9

The optoelectronic amplifier according to claim 2, wherein said negative resistance element has a first high-voltage low-current stable operation point and a second low-voltage high-current stable operation point which are determined by the resistance of said load means, the voltage-current characteristic of said negative resistance element and the magnitude of said power source, said negative resistance element changing its operation state from said first to said second stable point when light is applied to said control means.

Claim 10

The optoelectronic amplifier according to claim 2, wherein said load means further includes a load resistor connected in series with said light-emissive element so that the sum of the resistance of said load resistor and the forward resistance of said light-emissive element provides the load resistance for said negative resistance element.

Claim 11

The optoelectronic amplifier according to claim 2, wherein said light-emissive element is a PN junction light emitter and said negative resistance element is a tunnel diode.

Claim 12

The optoelectronic amplifier according to claim 9 wherein said light emitter and said tunnel diode are made of the same kind of semiconductor material.

Claim 13

The optoelectronic amplifier according to claim 9, wherein said light emitter and said tunnel diode are formed on separate portions of a single semiconductor base.

Claim 14

The optoelectronic amplifier according to claim 2, wherein said photoconversion element is a solar battery connected across said negative resistance element for converting the input light applied thereto into electric power.

Claim 15

The optoelectronic amplifier according to claim 7, which further comprises a switch element connected across said light-emissive element for selectively short-circuiting said light-emissive element.

Claim 16

An optoelectronic amplifier comprising: a negative resistance element the voltage-current characteristic of which has a peak current at a low voltage and a minimal current at a voltage higher than said low voltage so that the current-voltage characteristic has a peak and a valley therein; a DC power source for supplying power to said negative resistance element; a light-emissive means connected in series with said negative resistance element and said DC power source so as to be forwardly biased by said DC power source for generating light when a voltage applied thEreacross exceeds a threshold value and for biasing said negative resistance element at a first stable operation point lying in the region of said minimal current in the valley portion of said voltage-current characteristic; and a photoelectric conversion means having a high internal resistance in the absence of light impinging thereon and a low internal resistance in the presence of light impinging thereon, connected in parallel across said negative resistance element so as to be reversely biased by said DC power source through said light-emissive means and, in response to light impinging thereon, for shifting the biasing of said negative resistance element to a second stable operation point lying in the region of said peak current in the peak portion of said voltage-current characteristic, to thereby increase the forward current flowing through said light-emissive means above said threshold value, whereby an amplified light output is produced by said optoelectronic amplifier only in response to light impinging thereon.

Claim 17

An optoelectronic amplifier comprising: a negative resistance element the voltage-current characteristic of which has a peak current at a low voltage and a minimal current at a voltage higher than said low voltage so that the current-voltage characteristic has a peak and a valley therein; a DC power source for supplying power to said negative resistance element; a light-emissive means connected in series with said negative resistance element and said DC power source so as to be forwardly biased by said DC power source for generating light when a voltage applied thEreacross exceeds a threshold value and for biasing said negative resistance element at a first stable operation point lying in the region of said minimal current in the valley portion of said voltage-current characteristic; and a photoelectric conversion means having a high internal resistance in the absence of light impinging thereon and a low internal resistance in the presence of light impinging thereon, connected in parallel across said negative resistance element so as to be reversely biased by said DC power source through said light-emissive means and, in response to light impinging thereon, for shifting the biasing of said negative resistance element to a second stable operation point lying in the region of said peak current in the peak portion of said voltage-current characteristic, to thereby increase the forward current flowing through said light-emissive means above said threshold value, whereby an amplified light output is produced by said optoelectronic amplifier only in response to light impinging thereon.