US 5,517,351 A · Optical receiver apparatus

Abstract

Pumping light from a pumping laser diode is controlled by referring to both a peak value and a mark-space ratio value of an amplified signal. A peak value detecting circuit for the amplified signal light as well as a mark-space ratio detecting circuit for detecting the mark-space ratio are provided. The injection current to a semiconductor laser for pumping an erbium-doped optical fiber is controlled in accordance with a peak value when the mark-space ratio is in the vicinity of 0.5. When the mark-space ratio is beyond a predetermined range, for example 0.25 to 0.75, the injection current is fixed to a value obtained immediately before the mark-space ratio exceeds this range, to select the level fixing operation. Since the level fixing operation is carried out when the mark-space ratio is outside the predetermined range, the amplified signal light does not become excessive even when the mark-space ratio fluctuates. It thus becomes possible to prevent the detection failure of the received clock due to the breakdown of the receiving photodiode or optical noise.

Claims22

Dependent claims

An optical receiving apparatus, comprising:

amplifying means, which includes an optical fiber for light amplification and a pumping semiconductor laser diode which inputs pumping light to said optical fiber to amplify a received light signal and to output amplified light;
converting means for converting said amplified light into an electric signal;
and
control means for outputting a control signal for controlling the output of said pumping light from said pumping semiconductor laser diode
wherein said control means comprises means for setting said control signal based on a peak value of said electric signal and a mark-space ratio of said electric signal.

2 more elements

An optical receiving apparatus, comprising:

a pumping semiconductor laser which outputs pumping light;
a driving circuit for driving said semiconductor laser by controlling injection current to said pumping semiconductor laser based on externally supplied control current;
an optical fiber which receives said pumping light and amplifies an input signal light to output amplified signal light;
a receiving photodiode for converting said amplified signal light into an equalizing output signal to be output therefrom;
an amplifier for amplifying said equalizing output signal to output an equalizing amplified output signal;
a peak value detecting circuit which receives a part of said equalizing amplified output signal and detects a peak value of said output signal to output a peak value detection output;
a mark-space ratio detecting circuit which receives a part of said equalizing amplified output signal and detects a mean value of said output signal to output a mark-space ratio detection output;
and
a control circuit which receives said peak value detection output and said mark-space ratio detection output and controls said control current to said driving circuit.

6 more elements

An optical receiving apparatus, comprising:

a pumping semiconductor laser which outputs pumping light;
a driving circuit for driving said semiconductor laser by controlling injection current to said semiconductor laser based on externally supplied control current,
an optical fiber which receives said induction light and amplifies an input signal light to output amplified signal light;
an optical brancher for branching a part of said amplified signal light to output branch amplified light;
a first receiving photodiode which converts said branched amplified light into a reference current to be output therefrom;
a second receiving photodiode for converting said amplified signal light into an equalizing output signal to be output therefrom;
an amplifier for amplifying said equalizing output signal to output an equalizing amplified output signal;
a peak value detecting circuit which receives said equalizing amplified output and detects a peak value of said output signal to output a peak value detection output;
a mark-space ratio detecting circuit which receives said reference current and detects a mean value of said reference current to output a mark-space ratio detection output;
and
a control circuit for receiving said peak value detection output and said mark-space ratio detection output to control said control current to said driving circuit.

8 more elements

Dependencies are inferred from the claim text.

Optical receiver apparatus

Life of this patent

Optical receiver apparatus

Life of this patent

Abstract

Claims22