Optical signal measurement instrument and wide dynamic range optical receiver for use therein

An optical signal measurement instrument comprising:

• an optical splitter coupled to receive an optical input signal for producing first and second optical signals representative of the optical input signal with the first optical signal having a first optical power level being ten percent or less of the optical power of the optical input signal and the second optical signal having a second optical power level being fifty percent or more of the optical power of the optical input signal;
• a low sensitivity signal channel for converting the first optical signal into at least one voltage signal representative of a first portion of the optical input signal;
• a high sensitivity signal channel for converting the second optical signal into at least one voltage signal representative of a second portion of the optical input signal;
• means for converting the voltage signals from the respective low and high sensitivity signal channels into digital values representative of the various portions of the optical input signal;
• and
• means for combining the digital values representative of the various portions of the optical input signal to produce a composite digital output representative of the optical input signal.

An optical time domain reflectometer comprising:

• at least one optical signal generating device coupled to receive a current signal from a current drive circuit for generating an optical pulse output for launching into an optical fiber under test;
• an optical splitter coupled to receive an optical return signal from the fiber under test for producing first and second optical signals representative of the optical return signal with the first optical signal having a first optical power level being ten percent or less of the optical power of the optical return signal and the second optical signal having a second optical power level being fifty percent or more of the optical power of the optical return signal;
• means for coupling the optical pulse output into the optical fiber under test and the optical return signal into the optical splitter;
• a low sensitivity signal channel coupled to the optical splitter for converting the first optical signal into at least one voltage signal representative of a first portion of the optical return signal;
• a high sensitivity signal channel coupled to the optical splitter for converting the second optical signal into at least one voltage signal representative of a second portion of the optical return signal;
• means for converting the voltage signals from the respective low and high sensitivity signal channels into digital values representative of the first and second portions of the optical return signal;
• and
• means for combining the digital values representative of the voltage signals from the lower and high sensitivity signal channels to produce a composite digital representation of the optical return signal as a function of correlating in time the respective digital values representative of the first and second portions of the optical return signal and determining common overlapping regions between the various portions with no events where the low and high sensitivity signal channels are not noisy nor saturated.

An optical time domain reflectometer comprising:

• at least one optical signal generating device coupled to receive a current signal from a current drive circuit for generating an optical pulse output for launching into an optical fiber under test;
• an optical amplifier coupled to receive the optical pulse output from the optical signal generating device for producing an optical pulse output for launching into the fiber under test having an increased optical power level;
• an optical splitter coupled to receive an optical return signal from the fiber under test for producing first and second optical signals representative of the optical return signal with the first optical signal having a first optical power level being ten percent or less of the optical power of the optical return signal and the second optical signal having a second optical power level being fifty percent or more of the optical power of the optical return signal;
• means for coupling the optical pulse output into the optical fiber under test and the optical return signal into the optical splitter;
• a low sensitivity signal channel coupled to the optical splitter for converting the first optical signal into at least one voltage signal representative of a first portion of the optical return signal;
• a high sensitivity signal channel coupled to the optical splitter for converting the second optical signal into at least one voltage signal representative of a second portion of the optical return signal;
• means for converting the voltage signals from the respective low and high sensitivity signal channels into digital values representative of the first and second portions of the optical return signal;
• and
• means for combining the digital values representative of the voltage signals from the lower and high sensitivity signal channels to produce a composite digital representation of the optical return signal as a function of correlating in time the respective digital values representative of the first and second portions of the optical return signal and determining common overlapping regions between the various portions with no events and where the low and high sensitivity signal channels are not noisy nor saturated.

A method of generating a digital output representative of an optical input signal comprising:

• splitting the optical input signal into first and second optical signals with the first optical signal having ten percent of less of the optical power of the optical input signal and the second optical signal having fifty percent or more of the optical power of the optical input signal;
• converting the first optical signal into at least one voltage signal representative of a first portion of the optical input signal using a low sensitivity signal channel;
• converting the second optical signal into at least one voltage signal representative of a second portion of the optical input signal using a high sensitivity signal channel;
• converting the voltage signals from the respective low and high sensitivity signal channels into digital values representative of the various portions of the optical input signal;
• and
• combining the digital values representative of the various portions of the optical input signal to produce a composite digital output representative of the optical input signal.