Optical modulator, methods of manufacturing and operating the same and optical apparatus including the optical modulator

• US 8,675,272 B2
• Filed: 03/10/2010
• Issued: 03/18/2014
• Est. Priority Date: 06/17/2009
• Status: Expired due to Fees

• 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: Cho, Yong-chul, Jang, Jae-hyung, Park, Yong-hwa, Park, Chang-soo, Song, Jong-In
• Primary Examiner(s): SAHLE, MAHIDERE S
• Application Number:
  US12/720,795
• Publication Number:
  US 20100321755A1
• Time in Patent Office: 1,469 Days
• Field of Search: 359/238, 359/245, 359/248, 257 11- 27, 257/79, 257 94- 97, 257183-201
• US Class Current: 359/248
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G02F 1/01708 in an optical wavequide structure
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence

Abstract

An optical modulator, methods of manufacturing and operating the same, and an optical apparatus including the optical modulator are disclosed. The optical modulator includes an electro-optical converter and an optical-electric converter, stacked perpendicular to a substrate, and a gate transistor. The gate transistor gates a signal transmitted to the electro-optical converter from the optical-electric converter and allows charges generated in the optical-electric converter and charges remaining in the electro-optical converter to flow while bypassing the electro-optical converter when gating ON is performed.

Claims

1. An optical modulator comprising:

an electro-optical converter and an optical-electric converter, which are stacked in the direction perpendicular to a substrate; and

a gate transistor which, when gating ON is performed, gates a signal transmitted to the electro-optical converter from the optical-electric converter and allows charges generated in the optical-electric converter and charges remaining in the electro-optical converter to flow through the gate transistor while bypassing the electro-optical converter.

2. The optical modulator of claim 1, wherein

the electro-optical converter is one of a plurality of electro-optical converters, the optical-electric converter is one of a plurality of optical-electric converters, and the gate transistor is one of a plurality of gate transistors, and

the optical modulator further comprises an array comprising a plurality of unit pixels, wherein each of the plurality of unit pixels comprises a corresponding one of the plurality of optical-electric converters, a corresponding one of the plurality of electro-optical converters, and a corresponding one of the plurality of gate transistors.

3. The optical modulator of claim 2, further comprising a control unit which simultaneously controls the plurality of gate transistors of the array.

4. The optical modulator of claim 3, wherein the plurality of gate transistor and the control unit are connected to each other via a power transistor.

5. The optical modulator of claim 2, wherein

the array comprises a plurality of blocks, each one of the plurality of blocks comprising at least two of the plurality of unit pixels, and

for each of the plurality of blocks, gate transistors of the at least two of the plurality of unit pixels are simultaneously controlled.

6. The optical modulator of claim 1, further comprising a charge amplification unit disposed between the optical-electric converter and the electro-optical converter,

wherein an output terminal of the optical-electric converter is connected to the gate transistor and the charge amplification unit, and

wherein a unit pixel comprises the optical-electric converter, the electro-optical converter, the charge amplification unit, and the gate transistor.

7. The optical modulator of claim 1, further comprising:

a gate layer, which is an anode layer held in common by the optical-electric converter and the electro-optical converter, and

a unit pixel which comprises the optical-electric converter and the electro-optical converter,

wherein the gate transistor is connected to the gate layer and is disposed outside the unit pixel.

8. The optical modulator of claim 7, wherein the unit pixel is one of a plurality of unit pixels of an array, wherein the gate transistor is disposed outside the array.

9. The optical modulator of claim 8, wherein

the array comprises a plurality of blocks, and each of the plurality of blocks comprises at least two of the plurality of unit pixels, and

the gate transistor is one of a plurality of gate transistors, and the plurality of gate transistors are disposed outside the array such that each of the plurality of gate transistors corresponds to one of the plurality of blocks.

10. The optical modulator of claim 9, further comprising a plurality of loads disposed such that for each of the plurality of unit pixels, one of the plurality of loads is disposed between the unit pixel and the gate transistor corresponding to the one of the plurality of blocks of the unit pixel.

11. The optical modulator of claim 1, wherein the optical-electric converter comprises a heterojunction phototransistor (HPT) having a 2-port structure.

12. The optical modulator of claim 1, wherein the optical-electric converter comprises a heterojunction phototransistor (HPT) having a 3-port structure.

13. The optical modulator of claim 11, wherein the HPT comprises an emitter, a base, and a collector sequentially stacked on the electro-optical converter, and a collector of the gate transistor is connected to the emitter of the HPT.

14. The optical modulator of claim 11, wherein the HPT comprises a collector, a base, and an emitter sequentially stacked on the electro-optical converter, and an emitter of the gate transistor is connected to the collector of the HPT.

15. The optical modulator of claim 12, wherein the HPT comprises an emitter, a base, and a collector sequentially stacked on the electro-optical converter, and a collector of the gate transistor is connected to the base of the HPT.

16. The optical modulator of claim 6, wherein the gate transistor comprises a first heterojunction bipolar transistor (HBT), and the charge amplification unit comprises a second HBT.

17. The optical modulator of claim 7, wherein the optical-electric converter comprises an avalanche photodiode (APD).

18. A method of operating an optical modulator including an electro-optical converter, an optical-electric converter, and a gate transistor, the method comprising:

putting the gate transistor into an ON state by applying a gating voltage signal to a gate of the gate transistor, to gate a signal transmitted to the electro-optical converter from the optical-electric converter and allow charges generated in the optical-electric converter and charges remaining in the electro-optical converter to flow through the gate transistor while bypassing the electro-optical converter.

19. The method of claim 18, wherein the applying the gating voltage signal comprises supplying the gating voltage signal in a pulse waveform, a sinusoidal waveform or a triangular waveform.

20. An optical apparatus comprising an optical modulator, wherein the optical modulator comprises:

an electro-optical converter and an optical-electric converter, which are stacked perpendicular to a substrate; and

a gate transistor which, when gating ON is performed, gates a signal transmitted to the electro-optical converter from the optical-electric converter and allows charges generated in the optical-electric converter and charges remaining in the electro-optical converter to flow through the gate transistor while bypassing the electro-optical converter.

21. A method of manufacturing an optical modulator, the method comprising:

stacking an electro-optical converter and an optical-electric converter perpendicular to a substrate; and

forming a gate transistor and connecting the gate transistor to the electro-optical converter and the optical-electric converter such that when gating ON is performed, the gate transistor gates a signal transmitted to the electro-optical converter from the optical-electric converter, and allows charges generated in the optical-electric converter and charges remaining in the electro-optical converter to flow through the gate transistor while bypassing the electro-optical converter.

22. The method of claim 21, wherein the stacking the electro-optical converter and the optical-electric converter comprises:

forming the electro-optical converter; and

forming the optical-electric converter on the electro-optical converter.

23. The method of claim 21, wherein the stacking the electro-optical converter and the optical-electric converter comprises:

forming the optical-electric converter; and

forming the electro-optical converter on the optical-electric converter.

24. The method of claim 21, further comprising:

forming a charge amplification unit for amplifying charges generated in the optical-electric converter, and

connecting the charge amplification unit to an output terminal of the optical-electric converter, and

connecting the gate transistor to the output terminal of the optical-electric converter.

25. The method of claim 21, wherein, the stacking the electro-optical converter and the optical-electric converter comprises:

stacking at least an emitter layer, a base layer, and a collector layer in that order, to form the electro-optical converter, and

stacking at least an emitter layer, a base layer and a converter layer in that order, to form the electro-optical converter.

26. The method of claim 21, wherein, the stacking the electro-optical converter and optical-electric converter comprises:

stacking at least an emitter layer, a base layer, and a collector layer in that order, to form the electro-optical converter, and

stacking at least an emitter layer, a base layer, and a collector layer in that order, to form the optical-electric converter.

27. The method of claim 22, further comprising forming a gate layer between the optical-electric converter and the electro-optical converter, wherein the gate transistor and the gate layer are connected to each other.

28. The method of claim 21, wherein the optical-electric converter, the electro-optical converter, and the gate transistor form a unit pixel.

29. The method of claim 21, wherein the optical-electric converter and the electro-optical converter form a unit pixel.

30. The method of claim 24, wherein the optical-electric converter, the electro-optical converter, the gate transistor, and the charge amplification unit form a unit pixel.

31. The method of claim 21, wherein the optical-electric converter and the gate transistor are simultaneously formed.

32. The method of claim 24, wherein the optical-electric converter, the gate transistor, and the charge amplification unit are simultaneously formed.

33. The method of claim 21, wherein the optical-electric converter comprises a heterojunction phototransistor (HPT) having a 2-port structure or 3-port structure structure.

34. The method of claim 33, wherein the optical-electric converter comprises the HPT having the 2-port structure, and an emitter of the optical-electric converter and a collector of the gate transistor are connected to each other.

35. The method of claim 33, wherein the optical-electric converter comprises the HPT having the 2-port structure, and a collector of the optical-electric converter and an emitter of the gate transistor are connected to each other.

36. The method of claim 33, wherein, the optical-electric converter comprises the HPT having the 3-port structure, and a base of the optical-electric converter and a collector of the gate transistor are connected to each other.

37. The method of claim 24, wherein each of the optical-electric converter, the gate transistor, and the charge amplification unit comprises a corresponding heterojunction phototransistor (HPT), and an emitter of the optical-electric converter is connected to a collector of the gate transistor and a base of the charge amplification unit.

38. The method of claim 21, wherein the optical-electric converter comprises a photodiode or an avalanche photodiode (APD).