Circuit and method for measuring extinction ratio and controlling a laser diode transmitter based thereon
AssigneeAgere Systems Guardian Corp.
InventorsDaniel Mahgerefteh, Eva Peral
Life of this patent
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Abstract
A circuit for, and method of, measuring an extinction ratio of a laser diode and a laser diode transmitter incorporating the circuit or the method. In one embodiment, the circuit includes: (1) an RF power detector, optically couplable to an output of the laser diode, for producing a varying voltage that is a function of an AC portion of modulated power generated by the laser diode and (2) an error signal generator, coupled to the power detector, for integrating the varying voltage over time to yield an integrated DC voltage that is a function of the extinction ratio.
Claims20
A circuit for measuring an extinction ratio of a laser diode, comprising:
- an RF power detector, optically couplable to an output of said laser diode, for producing a varying voltage that is a function of an AC portion of modulated power generated by said laser diode;
- and
- an error signal generator, coupled to said power detector, for integrating said varying voltage over time to yield an integrated DC voltage that is a function of said extinction ratio.
A method of measuring an extinction ratio of a laser diode, comprising:
- producing a varying voltage that is a function of an AC portion of modulated power generated by said laser diode;
- and
- integrating said varying voltage over time to yield an integrated DC voltage that is a function of said extinction ratio.
A laser diode transmitter, comprising:
- a laser diode that is modulated with a string of bits to yield modulated optical power;
- a photodiode, in optical communication with said laser diode, that receives said modulated optical power;
- an RF power detector, coupled to said photodiode, for producing a varying voltage that is a function of an AC portion of said modulated power;
- and
- an error signal generator, coupled to said power detector, for integrating said varying voltage over time to yield an integrated DC voltage and generating an error signal that is a function of a comparison between said integrated DC voltage and a reference voltage, said integrated DC voltage being a function of said extinction ratio, said error signal employed to control a gain of said laser diode transmitter.
Dependencies are inferred from the claim text.