Patent ID: 8472805
Filing Date: 2013-06-25
Classification: H01S,H04J

Abstract:
1. A method for optical communications based on wavelength division multiplexing (WDM), comprising: providing tunable laser transmitter modules based on a common tunable laser transmitter module design which includes (1) a plurality of tunable laser modules to produce laser light at different optical WDM wavelengths to carry different WDM signal channels, respectively, each tunable laser module operable to tune a respective optical WDM wavelength, and (2) a beam combiner that includes input ports that are respectively coupled to receive the laser light from the tunable laser modules and an output port that combines the received laser light from the tunable laser modules into a combined optical output carrying light at the different optical WDM wavelengths, the beam combiner structured to exhibit a common transmission spectral profile from each input port to the output port that has periodic repetitive transmission bands that are adjacent to one another in wavelength and extend to cover different WDM sub-bands within a WDM band, wherein each transmission band has a spectral width to cover a predetermined number of WDM wavelengths, and wherein each tunable laser module includes a tunable laser that includes a tunable sampled grating distributed Bragg reflector (SG-DBR) laser which includes a substrate and a semiconductor structure formed on the substrate to include first and second sampled Bragg grating reflectors spaced from each other to form an optical resonator, a gain section between the first and second sampled Bragg grating reflectors that is electrically energized to produce an optical gain for the laser light and a phase section between the first and second sampled Bragg grating reflectors that is electrically controlled to control a phase of the laser light; applying an electrical control signal to the first sampled Bragg grating reflector to tune the first sampled Bragg grating reflector in tuning a wavelength of the laser light; maintaining the second sampled Bragg grating reflector in a fixed grating configuration when tuning the first sampled Bragg grating reflector to change the wavelength of the laser light, wherein the first sampled Bragg grating reflector is a high reflector to reflect the laser light and the second sampled Bragg grating reflector is spaced from the first sampled Bragg grating reflector and structured to form a partial reflector to the laser light to reflect part of the laser light back towards the first sampled Bragg grating reflector and to transmit part of the laser light as a laser output of the SG-DBR laser towards the beam combiner; operating the tunable laser transmitter modules to produce WDM optical signals at different optical WDM wavelengths in different WDM sub-bands, one tunable laser transmitter module producing laser light at optical WDM wavelengths per WDM sub-band, laser light at a respective optical WDM wavelength from each tunable laser transmitter module being modulated to produce a respective WDM optical signal carrying information of a respective WDM channel; and combining the WDM signals in the different WDM sub-bands from the tunable laser transmitter modules into a combined WDM optical output for transmission over a fiber link.