A multisection digital supermode-distributed Bragg reflector (MSDS-DBR) comprising: a plurality P of digital supermode Bragg reflector (DS-DBR) grating sections arranged along a waveguide; wherein each DS-DBR grating section is configured to pass or reflect light over a given spectral region, the given spectral region being different from the spectral regions of the other DS-DBR grating sections; wherein each DS-DBR grating section comprises a plurality M of grating sub-regions, each sub-region corresponding to a spectral sub-band within the spectral region of the DS-DBR grating section, and wherein each grating sub-region includes a positive electrical contact and a negative electrical contact; said grating sub-region being configured to pass or reflect light of its spectral sub-band when an electrical bias is provided between its positive and negative electrical contacts.

A driving condition for causing the tunable wavelength laser to conduct laser oscillation at a first wavelength is acquired. a driving condition for causing the tunable wavelength laser to conduct laser oscillation at the second wavelength is calculated. The tunable wavelength laser is driven based on the driving condition of the second wavelength, feedback control that changes the driving condition of the tunable wavelength laser based on a difference between an output of the wavelength sensing unit and the target value is performed, and the tunable wavelength laser is caused to oscillate at the second wavelength. The driving condition of the tunable wavelength laser obtained by the feedback control when oscillation has occurred at the second wavelength is stored in the memory. Thereafter, the tunable wavelength laser is driven with reference to the stored driving condition of the tunable wavelength laser.

A method to tune an emission wavelength of a wavelength tunable laser apparatus is disclosed. The laser apparatus implements, in addition to a wavelength tunable laser diode (t-LD) integrating with a semiconductor optical amplifier (SOA), a wavelength monitor including an etalon filter. The current emission wavelength is determined by a ratio of the magnitude of a filtered beam passing the etalon filter to a raw beam not passing the etalon filter. The method first sets the SOA in an absorbing mode to sense stray component disturbing the wavelength monitor, then correct the ratio of the beams by subtracting the contribution from the stray component.

A tunable wavelength laser comprising a laser cavity formed by a broadband mirror and a comb mirror. The laser cavity comprising a gain region. The laser cavity is configured such that a non-integer number of cavity modes of the laser cavity are between two consecutive reflection peaks of the comb mirror.

A parallel cavity tunable laser generally includes a semiconductor laser body defining a plurality of parallel laser cavities with a common output. Each of the parallel laser cavities is configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. The wavelength of the light generated in each of the laser cavities may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. The laser light generated in each selected one of the laser cavities is emitted from the common output at a front facet of the laser body. By selectively generating light in one or more of the laser cavities, one or more channel wavelengths may be selected for lasing and transmission.

A distributed feedback plus reflection (DFB+R) laser includes an active section, a passive section, a low reflection (LR) mirror, and an etalon. The active section includes a distributed feedback (DFB) grating and is configured to operate in a lasing mode. The passive section is coupled end to end with the active section. The LR mirror is formed on or in the passive section. The etalon includes a portion of the DFB grating, the passive section, and the LR mirror. The lasing mode of the active section is aligned to a long wavelength edge of a reflection peak of the etalon.

A two-section semiconductor laser includes a gain section and a modulation-independent grating section to reduce chirp. The modulation-independent grating section includes a diffraction grating for reflecting light and forms a laser cavity with the gain section for lasing at a wavelength or range of wavelengths reflected by the diffraction grating. The gain section of the semiconductor laser includes a gain electrode for driving the gain section with at least a modulated RF signal and the grating section includes a grating electrode for driving the grating section with a DC bias current independent of the modulation of the gain section. The semiconductor laser may thus be directly modulated with the modulated RF signal without the modulation significantly affecting the index of refraction in the diffraction grating, thereby reducing chirp.

Provided is a semiconductor laser device in which a distributed feedback laser part and an electro-absorption modulator part are formed on the same semiconductor substrate, and laser light emitted from the laser part is emitted from an emission end face of the modulator part. The laser part includes a first diffraction grating formed to extend in a direction of an optical axis of the laser light and the modulator part partially including a second diffraction grating formed to extend in the direction of the optical axis of the laser. A non-diffraction grating region in which a diffraction grating is not formed is interposed between the second diffraction grating of the modulator part and an emission end face of the laser part from which the laser light is emitted to the modulator part.

A reflector structure for a tunable laser and a tunable laser. A super structure grating is used as a reflector structure, and a suspended structure is formed around a region in which the super structure grating is located, to implement, using the suspended structure, thermal isolation around the region in which the super structure grating is located, and increase thermal resistance, such that less heat is lost, and heat is concentrated in the region in which the super structure grating is located, thereby improving thermal tuning efficiency of the reflector structure. Moreover, lateral support structures are disposed on two sides of the suspended structure, to provide a mechanical support for the suspended structure. In addition, regions in the super structure grating that correspond to any two lateral support structures on a same side of the suspended structure fall at different locations in a spatial period of the super structure grating.

A monolithically integrated optical device. The device has a gallium and nitrogen containing substrate member having a surface region configured on either a non-polar or semi-polar orientation. The device also has a first waveguide structure configured in a first direction overlying a first portion of the surface region. The device also has a second waveguide structure integrally configured with the first waveguide structure. The first direction is substantially perpendicular to the second direction.