The present invention relates to a semiconductor laser for use in an optical module for measuring distances and/or movements, using the self-mixing effect. The semiconductor laser comprises a layer structure including an active region (3) embedded between two layer sequences (1, 2) and further comprises a photodetector arranged to measure an intensity of an optical field resonating in said laser. The photodetector is a phototransistor composed of an emitter layer (e), a collector layer (c) and a base layer (b), each of which being a bulk layer and forming part of one of said layer sequences (1, 2). With the proposed semiconductor laser an optical module based on this laser can be manufactured more easily, at lower costs and in a smaller size than known modules.

Semiconductor device structures comprising laser diode cavities with at least one of a mode-selective filter and a phase-alignment element, and methods for their fabrication, are disclosed. An example device structure comprises a surface-etched grating distributed-feedback (SEG DFB) laser with a mode-selective reflector structure. The reflector structure is designed to provide higher pot feedback of the fundamental TE0 mode and suppression of higher order mode effects. The reflector structure may be a single interface (single facet) mirror type reflector comprising a spatially patterned reflector, or a multi-interface distributed Bragg reflector (DBR). A phase alignment element may be included to provide precise optical phase control. A photodetector for back-facet power monitoring may be included. A method of fabrication is disclosed, based on a self-aligned process in which DBR features are included on the same mask that is used for the DFB laser grating.

A monolithic QCL/APD IR Transceiver in which the QCL transmitter and APD receiver have the same N MQW stage composition and variation in thickness in the z direction for all positions in x and y directions. The heterostructure is configured via asymmetric stages, additional stages for the APD or by reversing the polarity of the p-n junction for the APD or a combination thereof such that the upper energy state in the QCL under forward bias is confined to the quantum well and in the APD under reverse bias is near the top of the quantum well in energy and localized in the quantum well to spatially overlap with the lower energy state to facilitate detection of echo photons. The QCL and APD may be positioned end-to-end, side-by-side or as a common region of the heterostructure.

According to an aspect, an optical system includes a laser diode configured to emit optical signals and at least two size-switchable broken racetrack ring resonators optically coupled to an optical waveguide, where each broken racetrack ring resonator is configured to exhibit a resonant wavelength. The optical system also includes a tuning arrangement associated with the broken racetrack ring resonators, where the tuning arrangement includes a micro electro-mechanical system (MEMS) or nano electro-mechanical system (NEMS) actuator mechanically coupled to a first portion of a first one of the broken racetrack ring resonators and configured to mechanically move the first portion so as to change the resonant wavelength of the first one of the broken racetrack ring resonators.

A method for producing an integrated micromechanical fluid sensor component includes forming a first wafer with a first Bragg reflector and with a light-emitting device on a first substrate. The light-emitting device is configured to emit light rays in an emission direction from a surface of the light-emitting device facing away from the first Bragg reflector. The method further includes forming a second wafer with a second Bragg reflector and with a photodiode on a second substrate. The photodiode is arranged on a surface of the second Bragg reflector facing towards the second substrate. The method also includes bonding or gluing the first wafer to the second wafer such that there is formed a cavity into which a fluid is introduced and through which the light rays can pass. The method further includes separating the fluid sensor component from the first and the second wafer.

Methods, systems, and apparatus, for optical communication. One apparatus includes a Fabry-Perot (FP) laser diode assembly coupled to a first port of a circulator; an optical amplifier coupled to a second port of the circulator; a wavelength division multiplexer (WDM) filter coupled to a third port of the circulator; and a Faraday rotator mirror coupled to the WDM filter.

An encoder includes an optical scale that is so provided as to be pivotable around a pivotal axis and includes a polarizing portion having a polarization characteristic, a light outputting portion that outputs linearly polarized light toward the polarizing portion, and a light detecting portion that detects the linearly polarized light from the optical scale. The light outputting portion includes a vertical cavity surface emitting laser, and light emitted from the vertical cavity surface emitting laser spreads at an angle greater than or equal to 5° but smaller than or equal to 20°.

A semiconductor optical integrated device according to the present invention includes a conductive substrate, a laser provided to the conductive substrate, a semi-insulating semiconductor layer provided on the conductive substrate, a photodiode provided on the semi-insulating semiconductor layer and a waveguide that is provided on the conductive substrate and guides output light of the laser to the photodiode, wherein an anode of the photodiode and a cathode of the photodiode are drawn from an upper surface side of the photodiode, and the waveguide and the photodiode are separated from each other by the semi-insulating semiconductor layer.

A Vertical Cavity Surface Emitting Laser (VCSEL) includes a layer stack of semiconductor layers having a first layer sub-stack forming a mesa, and a second layer sub-stack adjacent to the mesa in a stacking direction. Layers of the second layer sub-stack extend beyond layers of the first sub-stack in a direction perpendicular to the stacking direction. The semiconductor layers of the layer stack form an optical resonator having a first mirror, a second mirror, an active region between the first and second mirrors for laser light generation, and an oxide aperture layer forming a current aperture. The oxide aperture layer is made from Al.sub.1-xGa.sub.xAs with 0≤x≤0.05. The oxide aperture layer is a last layer of the mesa and immediately adjacent to a first layer of the second layer sub-stack. A first layer of the second layer sub-stack is a contact layer.

The present invention provides a method for estimating a condition parameter of a laser diode having an associated photodiode, to an apparatus for monitoring the operation of such a laser diode, and to a particle sensor apparatus. The photodiode (PD) is operable together with the laser diode (LD), wherein it detects the light (LS) of the laser diode (LD) and converts it into an electrical current, and is thermally coupled to the laser diode (LD). The at least one condition parameter is estimated during the operation of the laser diode (LD) and the estimation is based on current measurements and/or voltage measurements at the laser diode (LD) and/or at the photodiode (PD).