Method and apparatus to generate and monitor optical signals and control power levels thereof in a planar lightwave circuit

A method comprising:

• propagating optical signals through a plurality of waveguides included in a semiconductor substrate, the waveguides having formed therein a trench having a first sidewall and a second sidewall, the first and second sidewalls forming first and second angles with the optical signals propagation direction;
• receiving the optical signal using a photodetector array, the optical signal being propagated through the first sidewall and reflected from the second sidewall to the photodetector array;
• multiplexing optical signals passing through gratings using an arrayed waveguide grating (AWG) such that selected wavelengths defined by the gratings are multiplexed to a smelt output waveguide of the AWG;
• providing wavelength stabilization for a selected output wavelength;
• providing power usage equalization of a plurality of laser gain blocks;
• monitoring power of optical signals;
• and
• leveling the power of the optical signals by increasing and/or decreasing each optical signal to achieve a desired power level.

An apparatus comprising:

• an optical signal source array, each optical signal source to output an optical signal, a portion of which is propagated in a respective waveguide of a plurality of waveguides formed in a semiconductor substrate;
• a trench formed in the waveguides having a first sidewall and a second sidewall, the first and second sidewalls forming first and second angles with the optical signals propagation direction, the second sidewall having a reflective layer, the portion of the optical signal propagated in each of the waveguide being propagated through the first sidewall and reflected from the second sidewall;
• a photodetector array, each of the photodetector in the array to output a signal indicative of a power level of the portion of the optical signal reflected from the second sidewall;
• and a controller to provide, to the optical signal source array, a control signal responsive to the signal outputted by the photodetector array, each of the optical signal source to control a power level of the optical signal source responsive to the control signal;
• wherein
• the photodetector array coupled to the waveguides and a plurality of laser gain blocks, the photodetector array to provide wavelength stabilization for the waveguides, to provide power usage equalization of the plurality of laser gain blocks, to monitor power of optical signals, and to balance the power of the optical signals by increasing and/or decreasing each optical signal to achieve a desired power level.

A method comprising:

• generating optical signals;
• propagating a portion of each of the optical signal through a respective waveguide of a plurality of waveguides included in a semiconductor substrate, the waveguides having formed therein a trench having a first sidewall and a second sidewall, the first and second sidewalls forming first and second angles with the optical signals propagation direction;
• generating output signals responsive to a power level of the portion of each of the optical signal using a photodetector array, the portion of the optical signals being propagated through the first sidewall and reflected from the second sidewall each of to the photodetector;
• controlling a power level of the optical signal responsive to the output signal from each of the photodetector;
• multiplexing optical signals passing through gratings using an arrayed waveguide grating (AWG) such that selected wavelengths defined by the gratings are multiplexed to a single output waveguide of the AWG;
• providing wavelength stabilization for a selected output wavelength;
• providing power usage equalization of a plurality of laser gain blocks:
• monitoring power of optical signals;
• and
• leveling the power of the optical signals by increasing and/or deceasing each optical signal to achieve a desired power level.