Integrated wavelength locker
AssigneeJuniper Networks, Inc.
InventorsJohn Parker, Jared Bauters, Jonathan Edgar Roth, Erik Norberg, Greogry Alan Fish
Life of this patent
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Abstract
Described are various configurations of integrated wavelength lockers including asymmetric Mach-Zehnder interferometers (AMZIs) and associated detectors. Various embodiments provide improved wavelength-locking accuracy by using an active tuning element in the AMZI to achieve an operational position with high locking sensitivity, a coherent receiver to reduce the frequency-dependence of the locking sensitivity, and/or a temperature sensor and/or strain gauge to computationally correct for the effect of temperature or strain changes.
Claims20
A method for locking a frequency of a light source of a photonic integrated circuit using an integrated wavelength locker comprising an AMZI with an active tuning element in one interferometer arm, the method comprising:
- coupling light emitted by the light source into the AMZI at an input of the AMZI;
- adjusting a setting of the active tuning element to match a target setting stored in memory, the target setting being associated with a specified locking frequency;
- measuring a balanced photocurrent at an output of the AMZI;
- and
- tuning a frequency of the light source until the measured balanced photocurrent is substantially zero.
A method of manufacturing an integrated wavelength locker module, the method comprising:
- on a semiconductor substrate, creating a PIC comprising a tunable light source and a wavelength locker, the wavelength locker comprising an AMZI with two waveguide arms and a balanced receiver;
- and
- depositing a metal above one of the waveguide arms to form an active tuning element for adjusting an optical-path-length difference between the two waveguide arms.
A wavelength locker comprising:
- an athermal asymmetric Mach-Zehnder interferometer (AMZI) comprising an input coupler, two waveguide arms coupled to the input coupler at a first end of the waveguide arms, an output coupler coupled to the two waveguide arms at a second end of the waveguide arms and providing at least two output ports, and an active tuning element disposed in one of the waveguide arms and configured to adjust an optical-path-length difference between the two waveguide arms;
- at least one of a temperature sensor for measuring a temperature of the AMZI or a strain gauge for measuring a level of strain in the AMZI;
- at least two photodetectors each placed at a respective one of the at least two output ports, the at least two photodetectors forming, together with the output coupler, a balanced receiver;
- and
- memory storing temperature-dependent or strain-dependent target settings of the active tuning element for multiple temperatures of the AMZI or multiple levels of strain in the AMZI, the target settings corresponding to balanced photocurrents measured with the balanced receiver being substantially zero at a specified locking frequency and at respective measured temperatures or levels of strain.
Dependencies are inferred from the claim text.