In conventional hybrid lasers large back refection may lead to a degradation of relative intensity noise (RIN), linewidth broadening, mode hopping, etc. To solve the aforementioned problem a hybrid laser includes a mode converter for converting a higher-back-reflection mode of the light to a mode providing less back reflection to the gain chip. The mode converter may comprise a polarization rotator, a waveguide converter, or high-order mode converter. A routing waveguide may be provided including a phase shifter, e.g. a doped waveguide, for adjusting a cavity length of the laser cavity.

According to various aspects of the present disclosure, an apparatus is provided. In an aspect, the apparatus includes an optical transceiver having a first port, a second port and an optical switch coupled to the first port and the second port. The optical switch is switchable between a unidirectional port operation mode and a bidirectional port operation mode. When the optical switch is in the unidirectional port operation mode, the first port is configured to send a first optical signal, and the second port configured to receive a second optical signal. When the optical switch is in the bidirectional port operation mode, the first port configured to send the first optical signal and receive the second optical signal, and the second port configured to receive a third optical signal and not send the first signal. Furthermore, a second bidirectional port operation mode is supported with the second port configured to send the first optical signal and receive the second optical signal, and the first port configured to receive a third optical signal and not send the first signal.

An optical coupler (40; 50) comprises a substrate (41). A first waveguide element (45) is provided in a first layer with respect to the substrate, wherein the first waveguide element (45) comprises a first end (45a) and a second end (45b), and wherein the first end (45a) of the first waveguide element (45) is coupled to input/output light to/from a first end of the optical coupler. A second waveguide element (43) is provided in a second layer, the second layer arranged adjacent to the first layer, wherein the second waveguide element (43) comprises a first end (43a) and a second end (43b), and wherein the first end (43a) of the second waveguide element (43) is coupled to input/output light to/from a second end of the optical coupler. The first waveguide element (45) is configured to extend from the first end of the optical coupler towards the second end of the optical coupler, and the second waveguide element (43) is configured to extend from the second end of the optical coupler towards the first end of the optical coupler, such that the first waveguide element (45) partly overlaps with the second waveguide element (43) to adapt light passing between the first end (45a) of the first waveguide element (45) and first end (43a) of the second waveguide element (43).

According to various aspects of the present disclosure, an apparatus is provided. In an aspect, the apparatus includes an optical transceiver having a first port, a second port and an optical switch coupled to the first port and the second port. The optical switch is switchable between a unidirectional port operation mode and a bidirectional port operation mode. When the optical switch is in the unidirectional port operation mode, the first port is configured to send a first optical signal, and the second port configured to receive a second optical signal. When the optical switch is in the bidirectional port operation mode, the first port configured to send the first optical signal and receive the second optical signal, and the second port configured to receive a third optical signal and not send the first signal. Furthermore, a second bidirectional port operation mode is supported with the second port configured to send the first optical signal and receive the second optical signal, and the first port configured to receive a third optical signal and not send the first signal.

An optical semiconductor device including an optical waveguide; a light absorbing region coupled to the optical waveguide; a first conductive region and a second conductive region disposed at both sides of the light absorbing region so as to sandwich the light absorbing region; and a conductor coupled to the first conductive region and the second conductive region to let the first conductive region and the second conductive region short-circuit. With this configuration, the optical semiconductor device provides effects that absorption saturation less occurs even if the light intensity increases, so that reflection return light can be reliably suppressed without using an external power source.

An optical device and a method of manufacturing an optical device, including a ridge waveguide second, and a strip-loaded ridge waveguide section, comprises applying two different protective layers and two separate etches at two different depths. The protective layers overlap to protect the same section of the optical device, and to limit the surfaces of optical device to exposure to multiple etches, except at edges where the protective layers overlap.

A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

A system may include a polarization rotator combiner. The polarization rotator combiner may include a first stage, a second stage, and a third stage. The first stage may receive a first component of light with a TE00 polarization and a second component of light with the TE00 polarization. The first stage may draw optical paths of the first and second components together. The second stage may receive the first component and the second component from the first stage. The second stage may convert the polarization of the second component from the TE00 polarization to a TE01 polarization. The third stage may receive the first component and the second component from the second stage. The third stage may convert polarization of the second component from the TE01 polarization to a TM00 polarization. The third stage may output the first component and output the second component.

An optical fiber adapter and method of fabricating the same from a wafer including a double silicon-on-insulator layer structure. The optical fiber adapter may include a mode converter, a trench, and a V-groove, the V-groove and the trench operating as passive alignment features for an optical fiber, in the transverse translational and rotational degrees of freedom, and in the longitudinal translational degree of freedom, respectively. The mode converter may include a buried tapered waveguide.

An optical mode converter and method of fabricating the same from wafer including a double silicon-on-insulator layer structure. The method comprising: providing a first mask over a portion of a device layer of the DSOI layer structure; etching an unmasked portion of the device layer down to at least an upper buried oxide layer, to provide a cavity; etching a first isolation trench and a second isolation trench into a mode converter layer, the mode converter layer being: on an opposite side of the upper buried oxide layer to the device layer and between the upper buried oxide layer and a lower buried oxide layer, the lower buried oxide layer being above a substrate; wherein the first isolation trench and the second isolation trench define a tapered waveguide; filling the first isolation trench and the second isolation trench with an insulating material, so as to optically isolate the tapered waveguide from the remaining mode converter layer; and regrowing the etched region of the device layer.