TUNABLE LASER WITH CHANNEL SELECTOR
Systems and methods here may include improved tunable lasers having a tunable filter and a tunable channel selector that can control precisely the wavelength and the bandwidth of the light emitted by the laser, while suppressing light that may otherwise be emitted by the laser outside the desired wavelength and bandwidth with unidirectional ring lasers having a resonator of which forms a ring and where light propagates only in one of the two possible directions.
1 . A tunable laser comprising:
a ring-shaped laser cavity;
an infinite impulse response filter disposed inside the ring-shaped laser cavity; and
a tunable channel selector disposed inside the ring-shaped laser cavity, the tunable channel selector including multiple stages, wherein each of the multiple stages of the tunable channel selector are tuned to have transmission peaks at a pre-determined wavelength, wherein at least one of the multiple stages comprises a free spectral range that is at least twice a free spectral range of a previous stage included in the multiple stages, wherein a total roundtrip transmission through the infinite impulse response filter and the tunable channel selector are within a threshold range of an operating point.
2 . The tunable laser of claim 1 , wherein the total roundtrip transmission has no side modes of the operating point.
3 . The tunable laser of claim 1 , wherein each of the multiple stages includes a tunable Mach-Zhender interferometer.
4 . The tunable laser of claim 1 , further comprising a free space portion and a waveguide portion.
5 . The tunable laser of claim 4 , wherein the waveguide portion comprises the infinite impulse response filter.
6 . The tunable laser of claim 4 , wherein the waveguide portion comprises an output tap.
7 . The tunable laser of claim 6 , wherein the output tap is coupled to a power monitor, a modulator, or to a receiver.
8 . The tunable laser of claim 4 , further comprising:
the free space portion comprises an isolator.
9 . A tunable filter system comprising:
an infinite impulse response filter positioned in an incident laser beam, the infinite impulse response filter configured to intake the incident laser beam and split the incident laser beam to a through port and a loss port; and
multiple detectors positioned in the loss port, wherein each of the multiple detectors are configured to intercept the split portion of the incident laser beam, wherein each detector is configured to generate a detector signal, and wherein detector signals are generated such that a difference between the multiple detector signals generated by the multiple detectors is an error signal that indicates a degree of detuning of the incident laser beam.
10 . The tunable filter system of claim 9 , wherein any of a wavelength of the incident laser beam or the infinite impulse response filter is tunable to minimize a difference value between the detector signals generated by the multiple detectors.
11 . The tunable filter system of claim 9 , wherein the multiple detectors are disposed adjacent to an output waveguide in a semiconductor wafer.
12 . The tunable filter system of claim 11 , further comprising:
a lens positioned to collimate a beam from the output waveguide to generate a collimated beam, wherein the infinite impulse response filter includes a tilt and is configured to intercept the collimated beam and generate a reflected portion of the collimated beam that is incident on the multiple detectors.
13 . The tunable filter system of claim 12 , wherein the infinite impulse response filter is an etalon in a free space.
14 . A laser comprising:
a laser cavity; and
a photonic tuner, the photonic tuner including:
an integrated infinite impulse response filter; and
a tunable channel selector.
15 . The laser of claim 14 , wherein the photonic tuner further comprises:
an input waveguide; and
an output waveguide, wherein the input waveguide and the output waveguide include spot size converters for coupling light between the input waveguides and output waveguide.
16 . The laser of claim 15 , further comprising:
a tap photodiode configured to tap a portion of a light source from the input waveguide to a photodiode.
17 . The laser of claim 14 , further comprising an unbalanced chain of tunable Mach-Zhender interferometers (MZI).