OPTOELECTRONIC SHUTTER, METHOD OF OPERATING THE SAME AND OPTICAL APPARATUS INCLUDING THE OPTOELECTRONIC SHUTTER

• US 20100308211A1
• Filed: 12/22/2009
• Published: 12/09/2010
• Est. Priority Date: 06/04/2009
• Status: Active Grant

• Current Assignee: Gwangju Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Original Assignee: Gwangju Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Inventors: SONG, Jong-in, PARK, Yong-hwa, JANG, Jae-hyung, PARK, Chang-soo, CHO, Yong-chul
• Granted Patent: US 8,581,166 B2
• Time in Patent Office: Days
• US Class Current: 250/214R
• CPC Class Codes: G01N 21/41 Refractivity; Phase-affecting properties, e.g. optical path length G01N21/21 takes precedence
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14806 Structural or functional details thereof
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 31/153 formed in, or on, a common substrate
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: H05B 45/305 Frequency-control circuits
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

An optoelectronic shutter, a method of operating the same, and an optical apparatus including the optoelectronic shutter are provided. The optoelectronic shutter includes a phototransistor which generates an output signal from incident input light and a light emitting diode serially connected to the phototransistor. The light emitting diode outputs output light according to the output signal, and the output signal is gain-modulated according to a modulation of a current gain of the phototransistor.

Claims

1. An optoelectronic shutter comprising:

a phototransistor which generates an output signal from incident input light; and

a light emitting diode serially connected to the phototransistor,

wherein the light emitting diode outputs output light according to the output signal, and

wherein the output signal is gain-modulated according to a modulation of a current gain of the phototransistor.

2. The optoelectronic shutter of claim 1, wherein the light emitting diode and the phototransistor are stacked on a substrate in a vertical direction.

3. The optoelectronic shutter of claim 2, wherein the phototransistor is a heterojunction phototransistor having a triode structure.

4. The optoelectronic shutter of claim 2, wherein the light emitting diode comprises a P-type cladding layer, an active layer, and an N-type cladding layer that are sequentially stacked on the substrate, and the phototransistor comprises a collector layer, a base layer, and an emitter layer that are stacked sequentially on the light emitting diode.

5. The optoelectronic shutter of claim 4, wherein a direct current (DC) voltage supply source, which applies a DC bias voltage, is connected to a base of the phototransistor, and an alternating current (AC) voltage supply source, which applies an AC voltage for local oscillation of a base-emitter voltage, is connected to an emitter of the phototransistor, and a forward voltage is applied to the P-type cladding layer of the light emitting diode.

6. The optoelectronic shutter of claim 4, wherein an emitter electrode disposed on an upper portion of the emitter layer comprises a transparent conductive material, and the input light is incident on the emitter electrode.

7. The optoelectronic shutter of claim 6, wherein an anti-reflection (AR) layer is disposed on the emitter electrode.

8. The optoelectronic shutter of claim 4, wherein the optoelectronic shutter has a structure in which a plurality of unit pixels are arranged, and one of a plurality of phototransistors and one of a plurality of light emitting diodes constitute one of the unit pixels.

9. The optoelectronic shutter of claim 8, wherein a forward voltage is commonly applied to the P-type cladding layer of the light emitting diode of each of the plurality of unit pixels, a DC bias voltage is applied to a base of the phototransistor of each of the unit pixels, and an AC bias voltage for local oscillation of a base-emitter voltage is commonly applied to an emitter of the phototransistor of each of the unit pixels.

10. The optoelectronic shutter of claim 2, wherein the light emitting diode comprises an N-type cladding layer, an active layer, and a P-type cladding layer that are sequentially stacked on the substrate, and the phototransistor comprises an emitter layer, a base layer, and a collector layer that are stacked sequentially on the light emitting diode.

11. The optoelectronic shutter of claim 10, wherein a base current modulation unit is connected to a base of the phototransistor.

12. The optoelectronic shutter of claim 11, wherein the base current modulation unit comprises:

a first transistor which generates a current signal that is used to modulate the base current; and

a current source which generates a bias current that flows through the base of the phototransistor according to the current signal generated by the first transistor.

13. The optoelectronic shutter of claim 12, wherein an AC voltage for local oscillation of the base current is applied to a base of the first transistor, a collector of the first transistor is connected to a collector of the phototransistor, and an emitter of the first transistor is connected to the base of the phototransistor.

14. The optoelectronic shutter of claim 13, wherein the current source is a second transistor, a collector and a base of the second transistor are connected to the emitter of the first transistor, and an emitter of the second transistor is connected to ground or a negative voltage supply source.

15. The optoelectronic shutter of claim 14, wherein the first and second transistors are heterojunction bipolar transistors.

16. The optoelectronic shutter of claim 10, wherein a tunnel junction layer is interposed between the light emitting diode and the phototransistor.

17. The optoelectronic shutter of claim 8, wherein a collector electrode disposed on an upper portion of the collector layer comprises a transparent conductive material, and the input light is incident on the collector electrode.

18. The optoelectronic shutter of claim 13, wherein:

the optoelectronic shutter comprises a structure in which a plurality of pixels are arranged, and

one of a plurality of phototransistors, one of a plurality of first transistors, one of a plurality of current sources, and one of a plurality of light emitting diodes constitute one of the unit pixels.

19. The optoelectronic shutter of claim 18, wherein a ground voltage or a negative voltage is commonly applied to the N-type cladding layer of the light emitting diode of each of the plurality of unit pixels, a bias voltage is commonly applied to the collector of the phototransistor of each of the unit pixels, and an AC bias voltage for local oscillation of a base current is commonly applied to a base of the first transistor of each of the unit pixels.

20. The optoelectronic shutter of claim 2, wherein a reflection layer which reflects an output light emitted from the light emitting diode is interposed between the light emitting diode and the phototransistor.

21. The optoelectronic shutter of claim 20, wherein the reflection layer is a distributed Bragg reflector (DBR) layer.

22. The optoelectronic shutter of claim 2, wherein the substrate comprises glass, sapphire, or GaAs.

23. The optoelectronic shutter of claim 1, wherein the light emitting diode is a GaP-based red light emitting diode.

24. The optoelectronic shutter of claim 1, further comprising a capacitor disposed in parallel to the light emitting diode.

25. A method of operating an optoelectronic shutter including a phototransistor which generates an output signal from incident input light and a light emitting diode serially connected to the phototransistor, wherein the light emitting diode outputs output light according to the output signal, and the output signal is gain-modulated according to a modulation of a current gain of the phototransistor, the method comprising:

modulating a base-emitter voltage of the phototransistor to modulate a current gain of the phototransistor.

26. The method of claim 25, wherein a DC bias voltage is applied to a base of the phototransistor, and an AC voltage for local oscillation of the base-emitter voltage is applied to an emitter of the phototransistor.

27. The method of claim 25, wherein a modulation frequency of the base-emitter voltage is different from a modulation frequency of the input light.

28. A method of operating an optoelectronic shutter including a phototransistor which generates an output signal from incident input light and a light emitting diode serially connected to the phototransistor, wherein the light emitting diode outputs output light according to the output signal, and the output signal is gain-modulated according to a modulation of a current gain of the phototransistor, the method comprising:

modulating a base current of the phototransistor to modulate a current gain of the phototransistor.

29. The method of claim 28, wherein a modulation frequency of the base current is different from a modulation frequency of the input light.

30. An optical apparatus comprising an optoelectronic shutter, wherein the optoelectronic shutter comprises:

a phototransistor which generates an output signal from incident input light; and

a light emitting diode serially connected to the phototransistor,

wherein the light emitting diode outputs output light according to the output signal, and

wherein the output signal is gain-modulated according to a modulation of a current gain of the phototransistor.

31. The optical apparatus of claim 30, further comprising:

a light source which irradiates light onto an object;

an optical image sensor which receives the output light output from the optoelectronic shutter; and

a controller which controls the light source, the optoelectronic shutter, and the optical image sensor,

wherein the optoelectronic shutter gain-modulates light reflected by the object and outputs the output light, and the optical image sensor detects a phase delay of the light reflected by the object by sampling the output light.