LASER WITH WAVELENGTH-SELECTIVE REFLECTOR
A laser. In some embodiments, the laser includes an optical amplifier, and an output reflector. The output reflector may be configured to receive light from the optical amplifier and to reflect light at a first wavelength back toward the optical amplifier. The output reflector may include a wavelength-selective element, and a coupler configured to receive the light from the optical amplifier and to couple a portion of the light to the wavelength-selective element.
1 . A laser, comprising:
an optical amplifier; and
an output reflector,
the output reflector being configured to receive light from the optical amplifier and to reflect light at a first wavelength back toward the optical amplifier,
the output reflector comprising:
a wavelength-selective element, and
a coupler configured to receive the light from the optical amplifier and to couple a portion of the light to the wavelength-selective element.
2 . The laser of claim 1 , wherein the wavelength-selective element comprises an arrayed waveguide grating.
3 . The laser of claim 1 , wherein the arrayed waveguide grating has a free spectral range greater than 50 nm.
4 . The laser of claim 1 , wherein the wavelength-selective element comprises an echelle grating.
5 . The laser of claim 4 , wherein the echelle grating occupies less than 4 mm 2 .
6 . The laser of claim 4 , wherein the echelle grating has a 3 dB bandwidth of less than 0.6 nm.
7 . The laser of claim 1 , wherein:
the wavelength-selective element has a first port,
the optical amplifier is connected to a first port of the coupler, the first port of the coupler being at a first end of the coupler,
a third port of the coupler is connected to the first port of the wavelength-selective element, the third port of the coupler being at a second end of the coupler.
8 . The laser of claim 4 , wherein the wavelength-selective element is a Littrow echelle grating.
9 . The laser of claim 1 , wherein the wavelength-selective element further has a second port.
10 . The laser of claim 1 , wherein the second port of the wavelength-selective element is connected to a fourth port of the coupler, the fourth port of the coupler being at the second end of the coupler.
11 . The laser of claim 1 , wherein the wavelength-selective element is a composite wavelength-selective element comprising:
a first wavelength-selective element, and
a second wavelength-selective element.
12 . The laser of claim 11 , wherein the first wavelength-selective element is an arrayed waveguide grating.
13 . The laser of claim 11 , wherein the first wavelength-selective element is an echelle grating.
14 . The laser of claim 11 , wherein the second wavelength-selective element is a ring resonator.
15 . The laser of claim 14 , further comprising a tuning circuit configured to control a resonant wavelength of the ring resonator.
16 . The laser of claim 1 , wherein the coupler comprises a directional coupler.
17 . The laser of claim 1 , wherein the coupler comprises a Y-coupler.
18 . The laser of claim 1 , wherein the coupler is connected to the wavelength-selective element by a waveguide having a core comprising at least 70 atomic percent silicon.
19 . The laser of claim 1 , wherein the coupler is connected to the wavelength-selective element by a waveguide having a core comprising at least 35 atomic percent silicon and at least 35 atomic percent nitrogen.
20 . The laser of claim 19 , wherein the laser is capable of operating at a wavelength of less than 1 micron.
21 . The laser of claim 1 , configured to produce light at a first wavelength, the first wavelength being within 0.2 nm of a standard-specified wavelength.