Optical receiver and jitter tolerance control method

• US 20100316394A1
• Filed: 04/19/2010
• Published: 12/16/2010
• Est. Priority Date: 06/15/2009
• Status: Active Grant

• Current Assignee: Fujitsu Optical Components Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Optical Components Limited (Fujitsu Limited)
• Inventors: Koiwai, Yasushi
• Granted Patent: US 8,374,513 B2
• Time in Patent Office: Days
• US Class Current: 398/208
• CPC Class Codes: H04B 10/6911 Photodiode bias control, e.g. for compensating temperature variations
• CPC Class Codes: H04B 10/695 Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control

Abstract

An optical receiver includes an optical device that receives input light and converts the input light to an electric signal; an equivalent part that carries out waveform shaping on the electric signal; an amplifier that amplifies the electric signal; a discrimination part that discriminates data of the electric signal; an input optical power detecting part that detects input optical power of the input light; and a control part that makes an error rate in the electric signal with respect to the input optical power worse when the input optical power detected by the input optical power detecting part is equal to or less than a value corresponding to minimum receiver sensitivity.

Claims

1. An optical receiver, comprising:

an optical device configured to receive input light and convert the input light to an electric signal;

an equivalent part configured to carry out waveform shaping on the electric signal;

an amplifier configured to amplify the electric signal;

a discrimination part configured to discriminate data of the electric signal;

an input optical power detecting part configured to detect input optical power of the input light; and

a control part configured to make an error rate in the electric signal with respect to the input optical power worse when the input optical power detected by the input optical power detecting part is equal to or less than a value corresponding to minimum receiver sensitivity.

2. The optical receiver as claimed in claim 1, wherein:

the control part makes the error rate with respect to the input optical power worse by shifting a discrimination point used by the discrimination part to discriminate data of the electric signal from an optimum point according to the input optical power, when the input optical power detected by the input optical power detecting part is equal to or less than the value corresponding to the minimum receiver sensitivity.

3. The optical receiver as claimed in claim 2, further comprising:

an error rate detecting part configured to detect the error rate of the electric signal, the data of the electric signal being discriminated by the discrimination part, wherein

the control part shifts the discrimination point from the optimum point according to the input optical power, when the error rate detected by the error rate detecting part is equal to or less than the minimum receiver sensitivity.

4. The optical receiver as claimed in claim 2, wherein:

the control part keeps the discrimination point at a fixed point, when the input optical power detected by the input optical power detecting part is equal to or less than a predetermined value that is smaller than the value corresponding to the minimum receiver sensitivity.

5. The optical receiver as claimed in claim 1, wherein:

the control part makes the error rate with respect to the input optical power worse by lowering a bias voltage in the optical device from an optimum point according to the input optical power, when the input optical power detected by the input optical power detecting part is equal to or less than the value corresponding to the minimum receiver sensitivity.

6. The optical receiver as claimed in claim 5, further comprising:

an error rate detecting part configured to detect the error rate of the electric signal, the data of the electric signal being discriminated by the discrimination part, wherein

the control part lowers the bias voltage from the optimum point according to the input optical power, when the error rate detected by the error rate detecting part is equal to or less than the minimum receiver sensitivity.

7. The optical receiver as claimed in claim 5, wherein:

the control part keeps the bias voltage at a fixed voltage, when the input optical power detected by the input optical power detecting part is equal to or less than a predetermined value that is smaller than the value corresponding to the minimum receiver sensitivity.

8. The optical receiver as claimed in claim 1, wherein:

the control part makes the error rate with respect to the input optical power worse by lowering a cut-off frequency from an optimum point to narrow an equivalent band in the equivalent part according to the input optical power, when the input optical power detected by the input optical power detecting part is equal to or less than the value corresponding to the minimum receiver sensitivity.

9. The optical receiver as claimed in claim 8, further comprising:

an error rate detecting part configured to detect the error rate of the electric signal, the data of the electric signal being discriminated by the discrimination part, wherein

the control part lowers the cut-off frequency from the optimum point to narrow the equivalent band according to the input optical power, when the error rate detected by the error rate detecting part is equal to or less than the minimum receiver sensitivity.

10. The optical receiver as claimed in claim 8, wherein:

the control part keeps the equivalent band at a fixed band, when the input optical power detected by the input optical power detecting part is equal to or less than a predetermined value that is smaller than the value corresponding to the minimum receiver sensitivity.

11. A jitter tolerance control method in an optical receiver receiving input light and converting the input light to an electric signal in an optical device, carrying out waveform shaping on the electric signal, amplifying the electric signal, and discriminating data of the electric signal, the jitter tolerance control method comprising:

detecting input optical power of the input light; and

making an error rate in the electric signal with respect to the input optical power worse when the input optical power detected in the detecting is equal to or less than a value corresponding to minimum receiver sensitivity.

12. The jitter tolerance control method as claimed in claim 11, wherein:

the making the error rate with respect to the input optical power worse shifts a discrimination point used in the discriminating from an optimum point according to the input optical power, when the input optical power detected in the detecting is equal to or less than the value corresponding to the minimum receiver sensitivity.

13. The jitter tolerance control method as claimed in claim 11, wherein:

the making the error rate with respect to the input optical power worse lowers a bias voltage in the optical device from an optimum point according to the input optical power, when the input optical power detected in the detecting is equal to or less than the value corresponding to the minimum receiver sensitivity.

14. The jitter tolerance control method as claimed in claim 11, wherein:

the making the error rate with respect to the input optical power worse lowers a cut-off frequency to narrow an equivalent band used in an equivalent part that carries out waveform shaping on the electric signal from an optimum point according to the input optical power, when the input optical power detected in the detecting is equal to or less than the value corresponding to the minimum receiver sensitivity.