A method for testing a tunable wavelength laser device, which can suppress any error of light transmission characteristics of an etalon, and a tunable wavelength laser device are provided. The method for testing a tunable wavelength laser device is a method for testing a tunable wavelength laser device including a tunable wavelength laser and a wavelength sensing unit having an etalon. The testing method includes a first step of measuring a free spectral range interval of the etalon, a second step of acquiring a driving condition by tuning a wavelength to a target value provided between a top and a bottom of the free spectral range interval, and a third step of storing the driving condition in a memory.

An integrated circuit includes an optical reflector with one or two bus optical waveguides and a one-dimensional, photonic crystal nanobeam cavity to provide single-mode reflection with a narrow bandwidth. In particular, the nanobeam cavity may be implemented on a nanobeam-cavity optical waveguide (such as a channel or ridge optical waveguide), which is optically coupled to the one or two bus optical waveguides. The nanobeam-cavity optical waveguide may include notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide. Furthermore, a fill factor of the notches may vary as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define the nanobeam cavity.

An integrated circuit includes an optical reflector with one or two bus optical waveguides and a one-dimensional, photonic crystal nanobeam cavity to provide single-mode reflection with a narrow bandwidth. In particular, the nanobeam cavity may be implemented on a nanobeam-cavity optical waveguide (such as a channel or ridge optical waveguide), which is optically coupled to the one or two bus optical waveguides. The nanobeam-cavity optical waveguide may include notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide. Furthermore, a fill factor of the notches may vary as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define the nanobeam cavity.

A method for switching a wavelength of a tunable wavelength laser, which is provided with a temperature control device for an etalon and a wavelength detecting section for identifying a wavelength of the laser by a front/back ratio of the etalon, the wavelength of the laser being set in a target wavelength on the basis of a detection result of the wavelength detecting section, and the method comprises: driving the laser at a first wavelength; suppressing output of light of the laser in response to a command indicating an optical output at a second wavelength; starting control of the temperature control device towards a second etalon temperature corresponding to the second wavelength; and before the etalon reaches the second etalon temperature, detecting that the etalon reaches a temperature range corresponding to an allowable wavelength range corresponding to the second wavelength, and cancelling the suppression of light in response thereto.

A method to control a wavelength tunable laser diode (tunable LD) is disclosed. The tunable LD includes a SG-DFB region and a CSG-DBR region to tune the emission wavelength thereof. The CSG-DBR region includes three segments, where the refractive indices of respective segments are variable by heaters provided therein. When the electrical power supplied to two segments is optionally selected, the power supplied to the rest segment is corrected by an offset from a value reflecting physical dimensions of the heaters. The offset is determined such that the tunable LD shows the best side mode suppression ratio (SMSR).

A method for controlling a wavelength tunable laser is disclosed. The method comprises the steps of: calculating a lasing wavelength from two or more kinds of parameters, the parameters designating the target lasing wavelength; acquiring a driving condition from a memory, the wavelength tunable laser being operable to generate a laser beam of a first wavelength in the driving condition; and calculating another driving condition from the driving condition thus acquired and a wavelength difference between the first wavelength and a second wavelength, the second wavelength corresponding to the lasing wavelength, the wavelength tunable laser being operable to generate a laser beam of the second wavelength in the another driving condition, the wavelength tunable laser being driven in the another driving condition.

This disclosure describes an optical communication system for coupling light, via VCSEL or PCSEL, into a multilayer waveguide. The optical communication system comprises a plurality of emitters, a semi-insulating (SI) substrate, a plurality of electrical contacts, a plurality of waveguides, and a diffractive optical coupling system. The SI substrate supports the plurality of emitters. The plurality of electrical contacts are configured to individually modulate each emitter. The plurality of waveguides and the plurality of emitters are separated by an air gap. The diffractive optical coupling system is configured to direct emitted light from the plurality of emitters into the waveguides.