According to various embodiments, there is provided an optical device including a first waveguide configured to guide a light wave along a longitudinal axis; a first grating at least partially formed in the first waveguide, the first grating arranged away from the longitudinal axis in a first direction; and a second grating at least partially formed in the first waveguide, the second grating arranged away from the longitudinal axis in a second direction; wherein the second direction is different from the first direction.

A tunable laser for tuning a lasing mode based on light beams travelling through at least one block of channel waveguides with at least two tunable combs, includes: a frequency selective optical multiplexer comprising a first terminal for receiving/transmitting light, at least one block of channel waveguides, each channel waveguide having a reflectively coated first tail and a second tail, and an optical coupling element optically coupling the first terminal with the second tails of the channel waveguides of the at least one block of channel waveguides, each of the channel waveguides having a different length; a gain element generating a broad spectrum of light, the gain element coupling the first terminal of the frequency selective optical multiplexer with a reflective element.

The present invention discloses a semiconductor laser comprising an optical waveguide structure which may include a lower waveguide layer, an active layer of multiple quantum wells and an upper waveguide layer, which are successively stacked from bottom to top, a grating layer being formed on upper portion of the active layer, wherein the upper waveguide layer, a cladding layer and a contact layer are formed as a ridge which has a light incidence end surface and a light output end surface, wherein a beam expanding structure is formed on one end of the output end surface. The beam expanding structure has a beam expanding portion with a shape gradually contracted inwards from the light output end surface. Preferably, the beam expanding portion has a horizontal divergence angle of 5° to 20°.

An optical semiconductor device includes: an active region which includes an active layer which produces light when current is injected therein, a first diffraction grating layer having a first diffraction grating with a prescribed grating period, and a phase shift portion formed within the first diffraction grating layer, wherein the phase shift portion provides a phase shift not smaller than 1.5π but not larger than 1.83π; and a distributed reflection mirror region which is optically coupled to a first end of the active region as viewed along a direction of an optical axis, and which includes a second diffraction grating which reflects the light produced by the active region back into the active region.

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 semiconductor laser according to the present invention includes an active layer, a guide layer laminated on the active layer, a diffraction grating formed along a light emission direction in the guide layer, an upper electrode provided above the guide layer, and a lower electrode provided below the active layer. The diffraction grating includes a current-injection diffraction grating and current-non-injection diffraction gratings provided both in front of and in back of the current-injection diffraction grating. Phase shifters are individually provided at a central portion of the current-injection diffraction grating and at boundaries between the current-injection diffraction grating and the current-non-injection diffraction gratings. The upper electrode is provided above the current-injection diffraction grating and is not provided above the current-non-injection diffraction gratings.

A distributed feedback laser, including: an output end including an active region including a grating including a λ/4 phase-shift region; and a non-output end including a reflecting region including a grating with uniform period. The length of the active region is smaller than or equal to 200 μm. The end facet of the output end of the laser is coated with an anti-reflection film.

The invention relates to laser diode for generating laser radiation of at least two frequencies, comprising: a semiconductor body having a ridge waveguide; a DFB structure or DBR structure in the ridge waveguide; and a piezoelectric element for producing mechanical stress in the ridge waveguide, which piezoelectric element is arranged on the ridge waveguide. The invention further relates to a method for producing laser radiation of at least two frequencies by means of the laser diode.

Structures for response shaping in frequency and time domain, include an optical response shaper and/or a modulator device with multiple injection. The device comprises a resonator having an enclosed geometric structure, for example a ring or racetrack structure, at least two injecting optical waveguides approaching the resonator to define at least two coupling regions between the resonator and the injecting waveguides, and may define at least two Free Spectral Range states.

One or both of the coupling regions has a coupling coefficient selected for a predetermined frequency or time response, and the coupling coefficient or other device parameters may be variable, in some case in real time to render the response programmably variable.