Systems and methods reducing coherence effect in narrow line-width light sources

摘要

Systems and methods are described for reducing coherence effect in narrow line-width light sources through various modulation techniques. The systems and methods can include a narrow line-width laser source with a thermoelectric cooler thermally coupled thereto and a controller communicatively coupled to the thermoelectric cooler. The controller is configured to provide a varied input signal to the thermoelectric cooler to reduce coherence of the narrow line-width laser source by artificially broadening the narrow line-width on a time averaged basis. The systems and methods can also include direct modulation of the narrow line-width laser source. The systems and methods can include a narrow line-width Optical Time Domain Reflectometer (OTDR). The systems and methods can also include direct modulation of the narrow line-width laser source with or without the varied input signal to the thermoelectric cooler.

主权项

1. An optical time domain reflectometer (OTDR) system, comprising:
a narrow line-width laser source comprising a thermoelectric cooler thermally coupled thereto; a modulator configured to modulate the narrow line-width laser source; a device configured to couple an output of the narrow line-width laser source and the modulator to a device under test and an input from the device under test to a photo-detector; and a controller configured to provide an input signal to the thermoelectric cooler to monitor and adjust a light output of the narrow line-width laser source in a wavelength locking feedback loop and to concurrently dither the thermoelectric cooler to adjust the light output of the narrow line-width laser source by about 0.02 nm and reduce coherence to reduce noise in OTDR traces to levels comparable to a wide spectrum laser source OTDR; wherein the narrow line-width laser source, the thermoelectric cooler, and the controller are disposed in a channel line card that is a channel transceiver connected to a multiplexer configured to combine a Dense Wavelength Division Multiplexing (DWDM) output from the modulator in an optical communication system and are collectively configured to perform OTDR functionality in the optical communication system.