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 a semiconductor laser comprising a layer structure comprising an active zone, wherein the active zone is configured to generate an electromagnetic radiation, wherein the layer structure comprises a sequence of layers, wherein two opposite end faces are provided in a Z-direction, wherein at least one end face is configured to at least partly couple out the electromagnetic radiation, and wherein the second end face is configured to at least partly reflect the electromagnetic radiation, wherein guide means are provided for forming an optical mode in a mode space between the end faces, wherein means are provided which hinder a formation of an optical mode outside the mode space, in particular modes comprising a propagation direction which do not extend perpendicularly to the end faces.

A gain medium for semiconductor optical amplifier in high-power operation includes a substrate with n-type doping; a lower clad layer formed overlying the substrate; a lower optical confinement stack overlying the lower clad layer; an active layer comprising a multi-quantum-well heterostructure with multiple well layers characterized by about 0.8% to 1.2% compressive strain respectively separated by multiple barrier layers characterized by about −0.1% to −0.5% tensile strain. The active layer overlays the lower optical confinement stack. The gain medium further includes an upper optical confinement stack overlying the active layer, the upper optical confinement stack being set thinner than the lower optical confinement stack; an upper clad layer overlying the upper optical confinement stack; and a p-type contact layer overlying the upper clad layer.

The present disclosure provides a semiconductor optical signal amplifier for amplifying a light having an energy smaller than a band gap energy. The semiconductor optical signal amplifier includes: a first end surface; a second end surface, arranged apart from the first end surface; a first semiconductor region and a second semiconductor region, arranged between the first end surface and the second end surface; an active layer, arranged between the first end surface and the second end surface, and sandwiched between the first semiconductor region and the second semiconductor region, made of an indirect transition type semiconductor that amplifies a signal intensity of an input light by stimulated emission; a first electrode, connected to the first semiconductor region; and a second electrode, connected to the second semiconductor region and detecting a change in a carrier density in the active layer by a potential difference from the first electrode.

An optical transmitter capable of significantly suppressing a fluctuation in frequency response characteristics due to a fabrication error in internal wire length while reducing a subcarrier size of a module of the optical transmitter is provided. The optical transmitter includes: a subcarrier on which an RF wiring board, a modulated laser chip, and a terminating resistor are mounted and which has a ground pad on an upper surface thereof; and a wire for electrically connecting at least the RF wiring board and the modulated laser chip to each other, wherein the RF wiring board and the modulated laser chip are arranged in a width direction of the subcarrier, and a length of the wire in an electric path which starts at the RF wiring board, passes through the terminating resistor, and reaches the ground pad is 0.5 to 1.5 mm or an inductance of the wire is 0.4 to 1.2 nH.

A semiconductor optical amplifier array device includes: a substrate; and a plurality of semiconductor optical amplifiers formed on the substrate, each of the semiconductor optical amplifiers including an active region, and two input-output ports optically connected to the active region and disposed on same facet of the semiconductor optical amplifier array device. The plurality of semiconductor optical amplifiers include a first semiconductor optical amplifier in which length of the active region is equal to a first length, and a second semiconductor optical amplifier in which length of the active region is equal to a second length that is different from the first length.

Techniques for efficient alignment of a semiconductor laser in a Photonic Integrated Circuit (PIC) are disclosed. In some embodiments, a photonic integrated circuit (PIC) may include a semiconductor laser that includes a laser mating surface, and a substrate that includes a substrate mating surface. A shape of the laser mating surface and a shape of the substrate mating surface may be configured to align the semiconductor laser with the substrate in three dimensions.

A monolithic edge-emitting semiconductor diode array chip (100) comprises a one-dimensional array (70) of diode emitters (50), such as laser diodes, superluminescent diodes or semiconductor optical amplifiers. Semiconductor layers are arranged on a conductive substrate (1) and include active region layers (14) arranged between upper and lower cladding layers (12, 16) and separation layers (4, 5) arranged between the conductive substrate (1) and the lower cladding layer (16). The diode emitters (50) are formed by respective ridges (9) that are separated by trenches (25) which are sufficiently deep to penetrate into the separation layers (4, 5). Each diode (50) has its own upper and lower contacts (22, 24) that allow each diode (50) to be independently drivable with a current source driver circuit connected to push a modulated push current through its associated diode and/or a current sink connected to extract a modulated pull current through its associated diode.

A method for improving wide-band wavelength-tunable laser. The method includes configuring a gain region between a first facet and a second facet and crosswise a PN-junction with an active layer between P-type cladding layer and N-type cladding layer. The method further includes coupling a light excited in the active layer and partially reflected from the second facet to pass through the first facet to a wavelength tuner configured to generate a joint interference spectrum with multiple modes separated by a joint-free-spectral-range (JFSR). Additionally, the method includes configuring the second facet to have reduced reflectivity for increasing wavelengths. Furthermore, the method includes reconfiguring the gain chip with an absorption layer near the active layer to induce a gain loss for wavelengths shorter than a longest wavelength associated with a short-wavelength side mode. Moreover, the method includes outputting amplified light at a basic mode via the second facet.

In an embodiment a radiation emitting semiconductor chip includes a semiconductor layer sequence with a plurality of active regions and a main extension plane, wherein each active region has a main extension direction, wherein each active region is configured to emit electromagnetic radiation from an emitter region extending parallel to the main extension plane, wherein at least two active regions overlap in plan view, wherein the emitter regions are arranged at grid points of a regular grid connected by at least one grid line, and wherein the main extension direction of at least one active region encloses an angle of at least 10° and at most 80° with the grid lines of the regular grid.