External cavity widely tunable laser using a silicon resonator and micromechanically adjustable coupling
View Patent ↗A widely tunable laser is described where a compound semiconductor gain chip is coupled to a waveguide filter fabricated on silicon. The filter has two resonators with different free-spectral-ranges, such that Vernier tuning between the filters can be used to provide a single wavelength of light feedback into the gain chip, where the wavelength is adjustable over a wide range. The coupling between the gain chip and the filter is realized through a microlens whose position can be adjusted using micromechanics and locked in place.
1. An external cavity laser device, temperature controlled to produce a predominantly single output wavelength, comprising:
a semiconductor waveguide chip electrically activated to provide optical gain;
a second waveguide based device, of a different material and technology than the semiconductor waveguide chip, positioned to receive light of the semiconductor waveguide chip and provides a wavelength-selective optical feedback;
an optical element to collect and refocus light from the semiconductor waveguide chip into the second waveguide based device and refocus the optical feedback from the second waveguide based device into the semiconductor waveguide chip; and
further comprising at least one micromechanical arm coupled to the optical element, the micromechanical arm including a handle positioned away from the optical element such that movement of the handle results in movement of the lens that is reduced compared to movement of the handle.
2. The device of claim 1 , further comprising means for fixing position of the micromechanical arm.
3. The device of claim 2 , wherein at least a portion of the micromechanical arm is moveable absent application of the means for fixing position of the micromechanical arm.
4. The device of claim 1 , wherein the second waveguide-based device includes ring resonator filters fabricated in silicon.
5. The device of claim 4 wherein at least one of the ring resonator filters are tuned to vary the optical feedback to the semiconductor waveguide chip.