OPTICAL RECEIVER, OPTICAL LINE TERMINAL AND METHOD OF RECOVERING RECEIVED SIGNALS

• US 20100150561A1
• Filed: 11/24/2009
• Published: 06/17/2010
• Est. Priority Date: 12/12/2008
• Status: Abandoned Application

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: KIM, Byoung-shi, PARK, Man-yong, CHO, Seung-hyun
• Application Number:
  US12/625,299
• Publication Number:
  US 20100150561A1
• Time in Patent Office: Days
• US Class Current: 398/79
• CPC Class Codes: H04B 10/695 Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 2014/0253 Allocation of downstream wavelengths for upstream transmission

Abstract

An optical receiver is provided which can be applied to a wavelength division multiplexing passive optical network (WDM PON) based on a reflective semiconductor optical amplifier employing a wavelength reuse scheme. The optical receiver includes a photo diode to convert an optical signal to an electrical signal; a pre-amplifier to linearly amplify the electrical signal and convert the amplified electrical signal to a voltage signal; a post-amplifier, which is equipped with a gain control function, to convert the voltage signal to a signal with a constant output level and to control a decision threshold of the converted signal; and an offset voltage generator to generate a predetermined offset voltage for the decision threshold control of the post-amplifier and to provide the offset voltage to the post-amplifier. Accordingly, it is possible to increase an extinction ratio of a downstream optical signal to a predetermined level in the WDM PON based on a reflective semiconductor optical amplifier employing a wavelength reuse scheme, and it is possible to reduce an optical power, which is received by the reflective semiconductor optical amplifier incorporated in a subscriber terminal, below a predetermined level. As a result, it is possible to improve transmission quality of the downstream and upstream optical signals.

Claims

1. An optical receiver comprising:

a photo diode to convert an optical signal to an electrical signal;

a pre-amplifier to linearly amplify the electrical signal and convert the amplified electrical signal to a voltage signal;

a post-amplifier, which is equipped with a gain control function, to convert the voltage signal to a signal with a constant output level and to control a decision threshold of the converted signal; and

an offset voltage generator to generate a predetermined offset voltage for the decision threshold control of the post-amplifier and to provide the offset voltage to the post-amplifier.

2. The optical receiver of claim 1, wherein the post-amplifier comprises:

a first post-amplifying part, which is equipped with a gain control function, to convert the voltage signal to a signal with a constant output level; and

a second post-amplifying part to control a decision threshold of the signal with the constant output level which is output from the first post-amplifying part.

3. The optical receiver of claim 1, wherein the pre-amplifier is a continuous-mode pre-amplifier.

4. The optical receiver of claim 1, wherein the pre-amplifier is a burst-mode pre-amplifier.

5. The optical receiver of claim 1, wherein the offset voltage generator comprises:

a voltage regulator to output a constant voltage; and

a voltage divider to produce an output voltage which is a fraction of the constant voltage from the voltage regulator.

6. The optical receiver of claim 5, wherein the voltage divider comprises a variable resistor configured to vary a resistance.

9. The optical line terminal of claim 1, wherein the offset voltage generator comprises:

a voltage regulator to output a constant voltage; and

a voltage divider to produce an output voltage which is a fraction of the constant voltage from the voltage regulator.

10. The optical line terminal of claim 9, wherein the voltage divider comprises a variable resistor configured to vary a resistance.

7. An optical line terminal in a wavelength division multiplexing passive optical network (WDM PON) based on a reflective semiconductor optical amplifier employing a wavelength reuse scheme, comprising:

a photo diode to convert an optical signal, which is received from a plurality of optical network terminals or optical network units, to an electrical signal of a current type;

a pre-amplifier to linearly amplify the electrical signal and convert the amplified electrical signal to a voltage signal;

a post-amplifier, which is equipped with a gain control function, to convert the voltage signal to a signal with a constant output level and control a decision threshold of the converted signal;

a signal processor to analyze and process the converted signal output from the post-amplifier, and

an offset voltage generator to generate a predetermined offset voltage for the decision threshold control of the post-amplifier and to provide the offset voltage to the post-amplifier.

8. The optical line terminal of claim 7, wherein the post-amplifier comprises:

a first post-amplifying part, which is equipped with a gain control function, to convert the voltage signal to a signal with a constant output level; and

a second post-amplifying part to control a decision threshold of the signal with the constant output level which is output from the first post-amplifying part.

11. A method of recovering a received signal in a wavelength division multiplexing passive optical network (WDM PON) based on a reflective semiconductor optical amplifier employing a wavelength reuse scheme, comprising:

converting a received optical signal to an electrical signal;

linearly amplifying the electrical signal and converting the amplified electrical signal to a voltage signal;

amplifying the voltage signal to a signal with a constant output level;

controlling a decision threshold of the amplified output signal based on predetermined data.

12. The method of claim 11, wherein controlling the decision threshold comprises:

receiving predetermined data for the decision threshold control; and

generating and providing an offset voltage for the decision threshold control according to the predetermined data.