A symmetric distributed feedback (DFB) laser that is integrated in a silicon based photonic integrated circuit can output light from both sides of the symmetric DFB laser onto waveguides. The light in the waveguides can be phase adjusted and combined using an optical coupler. The symmetric DFB laser can generate light and symmetrically output light onto different lanes of a multi-lane transmitter.

The invention relates to a method for fabricating a semiconductor structure. The method comprises fabricating a photonic crystal structure of a first material, in particular a first semiconductor material and selectively removing the first material within a predefined part of the photonic crystal structure. The method further comprises replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy. The one or more second materials may be in particular semiconductor materials. The invention further relates to devices obtainable by such a method.

A non-etched gap is introduced along the length of an integrated Bragg grating with etched grooves such that the coupling coefficient, K, of the grating is reduced by the non-etched gap. In this way, multiple grating K values may be defined within a photonic integrated circuit using a single lithography and etch step. Additionally, the non-etched gap width may be varied along the length of a single grating to implement a chirped grating.

An optical element includes a distributed Bragg reflector, wherein the distributed Bragg reflector includes a first-order diffraction grating of a first-order period disposed in a central region, and second-order diffraction gratings of a second-order period having a coupling coefficient smaller than a coupling coefficient of the first-order diffraction grating and disposed in both end regions between which the central region is located.

Single-mode distributed-feedback (DFB) lasers including single mode DFB waveguides with tapered grating structures are provided herein. Tapered grating structures provide for single mode DFB waveguides with predictable single mode operation. Uniform grating structures may provide for single mode operation, however DFB waveguides implementing uniform grating structures may operate at one of two single modes. Advantageously, DFB waveguides with tapered gratings operate with a spectrally narrow single mode at the same predictable single mode for all DFB waveguides with substantially identical specifications. Such predictability may lead to increased yield during manufacture of DFB waveguides with tapered gratings.

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 distributed reflector (DR) laser may include a distributed feedback (DFB) region and a distributed Bragg reflector (DBR). The DFB region may have a length in a range from 30 micrometers (μm) to 100 μm and may include a DFB grating with a first kappa in a range from 100 cm.sup.−1 to 150 cm.sup.−1. The DBR region may be coupled end to end with the DFB region and may have a length in a range from 30-300 μm. The DBR region may include a DBR grating with a second kappa in a range from 150 cm.sup.−1 to 200 cm.sup.−1. The DR laser may additionally include a lasing mode and a p-p resonance frequency. The lasing mode may be at a long wavelength side of a peak of a DBR reflection profile of the DBR region. The p-p resonance frequency may be less than or equal to 70 GHz.

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 high-power semiconductor chip and a preparation method therefor. The semiconductor chip comprises: a substrate (1), a lower confinement layer (2), a lower waveguide layer (3), an active layer (4), an upper waveguide layer (5), a lateral grating layer (10), an upper confinement layer (6), a contact layer (7), a current isolation dielectric layer (8) and a metal layer (9), sequentially arranged from bottom to top, wherein the lateral grating layer (10) comprises a plurality of groups of lateral gratings; the plurality of groups of lateral gratings are sequentially arranged in a first direction; the periods of the plurality of groups of lateral gratings are different from each other; each group of lateral gratings comprises a plurality of gratings; the plurality of gratings are arranged in a second direction; and the first direction intersects with the second direction. Providing a lateral grating layer (10) in a waveguide improves the propagation loss of the high-order lateral light mode in the waveguide, and achieves the aim of suppressing the lasing of the high-order lateral light mode; and providing a plurality of groups of gratings with different periods suppresses the lasing of an intensity oscillation light mode caused by single grating gain modulation and refractive index modulation, achieves the effect of suppressing lateral light intensity periodic oscillation and eliminates the formation of far-field double humps.

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.