System and Method for Multi-Wavelength Optical Signal Detection

• US 20150214388A1
• Filed: 01/08/2015
• Published: 07/30/2015
• Est. Priority Date: 01/27/2014
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: U.S.A. as represented by the Administrator of the National Aeronautics and Space Administration
• Inventors: McGlone, Thomas D.
• Granted Patent: US 9,696,411 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4913 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 31/02019 for devices characterised by at least one potential jump barrier or surface barrier

Abstract

The system and method for multi-wavelength optical signal detection enables the detection of optical signal levels significantly below those processed at the discrete circuit level by the use of mixed-signal processing methods implemented with integrated circuit technologies. The present invention is configured to detect and process small signals, which enables the reduction of the optical power required to stimulate detection networks, and lowers the required laser power to make specific measurements. The present invention provides an adaptation of active pixel networks combined with mixed-signal processing methods to provide an integer representation of the received signal as an output. The present invention also provides multi-wavelength laser detection circuits for use in various systems, such as a differential absorption light detection and ranging system.

Claims

1. A multi-wavelength optical signal detector, comprising:

photodiode configured to output charge flux in response to a multi-wavelength optical signal incident on the photodiode;

a current-to-charge converter connected to the photodiode and configured to receive the charge flux from the photodiode and output a first voltage proportional to a charge accumulated;

a delta-sigma modulator (DSM) connected to the current-to-charge converter and configured to receive the first voltage from the current-to-charge converter and output pulses based at least in part on the first voltage; and

a pulse counter connected to the DSM and configured to receive the pulses from the DSM and output a digital signal based at least in part on the pulses.

2. The multi-wavelength optical signal detector of claim I, wherein the DSM maintains a quasi-static charge balance on a summing capacitor over a window including a quantity of N clock periods.

3. The multi-wavelength optical signal detector of claim 2, wherein a number of the pulses within the window is M and a signal information of the output digital signal is M/N.

4. The multi-wavelength optical signal detector of claim 3, wherein the output digital signal is an encoded binary signal.

5. The multi-wavelength optical signal detector of claim 4, wherein an unpadded area of the multi-wavelength optical signal detector is 500×

300 micrometers (um).

6. The multi-wavelength optical signal detector of claim 5, wherein the multi-wavelength optical signal is a laser.

7. A multi-wavelength optical signal detection system, comprising:

an optical receiver, comprising;

an electronic component, comprising;

a photodiode configured to output charge flux in response to a multi-wavelength optical signal incident on the photodiode;

a current-to-charge converter connected to the photodiode and configured to receive the charge flux from the photodiode and output a first voltage proportional to a charge accumulated;

a delta-sigma modulator (DSM) connected to the current-to-charge converter and configured to receive the first voltage from the current-to-charge converter and output pulses based at least in part on the first voltage; and

a pulse counter connected to the DSM and configured to receive the pulses from the DSM and output a digital signal based at least in part on the pulses; and

a processor connected to the electronic component and configured to receive the digital signal from the pulse counter; and

an optical transmitter, comprising a laser configured to output the multi-wavelength optical signal.

8. The multi-wavelength optical signal detection system of claim 7, wherein the DSM maintains a quasi-static charge balance on a summing capacitor over a window including a quantity of N clock periods.

9. The multi-wavelength optical signal detection system of claim 8, wherein a number of the pulses within the window is M and a signal information of the output digital signal is M/N.

10. The multi-wavelength optical signal detection system of claim 9, wherein the output digital signal is an uncoded binary signal.

11. The multi-wavelength optical signal detection system of claim 10, wherein an unpadded area of the electronic component is 500×

300 micrometers (um).

12. The multi-wavelength optical signal detection system of claim 11, wherein the multi-wavelength optical signal detection system is a differential absorption light detection and ranging system.

13. The multi-wavelength optical signal detection system of claim 12, wherein the photodiode comprises four photodiodes bump bonded to a silicon die including a signal channel for each of the four photodiodes.

14. The multi-wavelength optical signal detection system of claim 13, wherein the four photodiodes are made of different materials.

15. A method for multi-wavelength optical signal detection, comprising:

receiving a multi-wavelength optical signal at a photodiode;

outputting charge flux from the photodiode to a current-to-charge convener in response to the multi-wavelength optical signal incident on the photodiode;

receiving the charge flux from the photodiode at a current-to-charge converter and outputting a first voltage proportional to a charge accumulated from the current-to-charge converter to a delta-sigma modulator (DSM);

receiving the first voltage from the current-to-charge converter at the DSM and outputting pulses based at least in part on the first voltage from the DSM to a pulse counter; and

receiving the pulses from the DSM at the pulse counter and outputting a digital signal based at least in part on the pulses.

16. The method of claim 15, wherein the DSM Maintains a quasi-static charge balance on a summing capacitor over a window including a quantity of N clock periods.

17. The method of claim 16, wherein a number of the pulses within the window is M and a signal information of the output digital signal is M/N.

18. The method of claim 17, wherein the output digital signal is an uncoded binary signal.

19. The method of claim 17, wherein the multi-wavelength optical signal is a laser.

20. The method of claim 19, wherein:

the photodiode comprises four photodiodes bump bonded to a silicon die including a signal channel for each of the four photodiodes; and

the four photodiodes are made of different materials.