Integrated high-power tunable laser with adjustable outputs
A tunable laser that includes an array of parallel optical amplifiers is described. The laser may also include an intracavity N×M coupler that couples power between a cavity mirror and the array of parallel optical amplifiers. Phase adjusters in optical paths between the N×M coupler and the optical amplifiers can be used to adjust an amount of power output from M−1 ports of the N×M coupler. A tunable wavelength filter is incorporated in the laser cavity to select a lasing wavelength.
1. An optical receiving system comprising:
a first cavity reflector of a laser formed on a first substrate that is formed of a first semiconductor material;
at least one second cavity reflector of the laser formed on a second substrate that is formed of a second semiconductor material that is different from the first semiconductor material;
a plurality of optical paths within the laser extending between the first cavity reflector and the at least one second cavity reflector;
an N×M coupler formed in the laser on the first substrate and coupled to the plurality of optical paths, wherein N and M are nonzero integers and N is greater than or equal to 2;
plural optical amplifiers formed on the second substrate in at least two optical paths of the plurality of optical paths; and
a coherent optical receiver formed on the first substrate and having an optical port connected to an output port from the laser.
2. The optical receiving system of claim 1 , wherein the laser is configured to provide a local oscillator signal to the coherent optical receiver.
3. The optical receiving system of claim 2 , wherein the coherent optical receiver comprises an integrated phase-diverse photonic circuit.
4. The optical receiving system of claim 2 , wherein the coherent optical receiver comprises an integrated polarization-diverse photonic circuit.
5. The optical receiving system of claim 1 , wherein the N×M coupler is arranged in the laser to receive light from the first cavity reflector at a first port of the N×M coupler and to distribute the light to N output ports of the N×M coupler, where N and M are both greater than 1.
6. The optical receiving system of claim 5 , wherein plural output ports of the N output ports connect to the at least two optical paths.
7. The optical receiving system of claim 5 , wherein the first substrate comprises a silicon photonics chip and the second substrate comprises an indium-phosphide chip.
8. The optical receiving system of claim 5 , further comprising:
first microfabricated waveguides coupled to at least some of the N output ports; and
second microfabricated waveguides coupled to the plural optical amplifiers.
9. The optical receiving system of claim 8 , further comprising mode-size adapters located between the first microfabricated waveguides and second microfabricated waveguides.
10. The optical receiving system of claim 8 , wherein the first microfabricated waveguides are butt-coupled to the second microfabricated waveguides.
11. The optical receiving system of claim 8 , wherein the first microfabricated waveguides are integrated on the first substrate and the second microfabricated waveguides are integrated on the second substrate.
12. The optical receiving system of claim 5 , further comprising:
M−1 power ports connected to the N×M coupler; and
a phase shifter in a first optical path of the plurality of optical paths, wherein the phase shifter is adjustable to alter an amount of power from at least one of the M−1 power ports.
13. The optical receiving system of claim 12 , further comprising:
a detector arranged to sense an optical power from one of the M−1 power ports; and
a feedback circuit arranged to receive a power signal from the detector and alter a phase of the phase shifter responsive to the received power signal.
14. The optical receiving system of claim 12 , wherein a first of the M−1 power ports is connected to the coherent optical receiver, and wherein a second of the M−1 power ports is connected to an optical transmitter that is integrated on the first substrate.
15. The optical receiving system of claim 14 , wherein the optical transmitter comprises a pair of nested Mach-Zehnder interferometers.
16. A method of receiving optical signals, the method comprising:
generating a local oscillator signal by a laser that includes a first cavity reflector formed on a first substrate of a first semiconductor material, at least one second cavity reflector formed on a second substrate of a second semiconductor material that is different from the first semiconductor material, a plurality of optical paths within the laser extending between the first cavity reflector and the at least one second cavity reflector, an N×M coupler formed in the laser on the first substrate and coupled to the plurality of optical paths wherein N and M are nonzero integers and N is greater than or equal to 2, and plural optical amplifiers formed on the second substrate in at least two optical paths of the plurality of optical paths;
receiving the optical signals by a coherent optical receiver that is formed on the first substrate and connected to an output port from the laser; and
receiving the local oscillator signal by the coherent optical receiver.
17. The method of claim 16 , further comprising providing the optical signals and the local oscillator signal to a phase-diverse photonic circuit of the coherent optical receiver.
18. The method of claim 16 , further comprising providing the optical signals and the local oscillator signal to a polarization-diverse photonic circuit of the coherent optical receiver.
19. The method of claim 16 , further comprising adjusting an amount of power in the local oscillator signal by adjusting at least one phase shifter located in at least one optical path of the plurality of optical paths.
20. The method of claim 16 , further comprising:
generating a carrier wave with the laser; and
providing the carrier wave to an optical transmitter that is formed on the first substrate.