Abstract: A high speed, compact and reliable semiconductor device for spatially switching light in optical switching networks, optical computers and optical interconnection networks is provided. The semiconductor device for spatially switching light comprises stacked P-anode, inner n-base, inner p-base and cathode layers, with an anode cathode on the P-anode layer defining a ridge. A low reverse bias is provided by a biasing means connected to a gate electrode disposed on a ledge of one base layer. A light emission region on the gate electrode side emits light, and a current flow induces a transversely flowing, narrow, light emitting channel that can be spatially shifted by switching the single gate electrode's bias. A high reverse bias also provides a spatially shifted light emission region in another part of the device's face.

Abstract: A optical medium, such as an angled distributed reflector, e.g., an angular grating, or .alpha.-DFB laser diode or a waveguide wavelength selective filter, has a mean optical axis defining an optical cavity for substantially confined light propagation within the device. An angular grating is provided in at least a portion of the optical cavity forming a grating region permitting light to propagate along the optical cavity in two coupled waves or modes incident along the angular grating, a first incident propagating wave substantially parallel with respect to the mean optical axis and a second incident propagating wave at an angle with respect to the mean optical axis.

Abstract: In a semiconductor laser having an active layer and a cladding structure interposing the active layer, the cladding structure includes a saturable absorbing layer, and the saturable absorbing layer is formed of InGaAsP.

Abstract: A pulse width modulation and intensity modulation signal generating unit, based on input data, performs pulse width modulation and intensity modulation and generates a light emission instruction signal. An error amplifier forms a negative feedback loop together with a semiconductor laser and a light reception device which monitors light output of the semiconductor laser, the error amplifier controlling forward current of the semiconductor laser so that a light reception signal proportional to the light output of the semiconductor laser is equal to the light emission instruction signal. A current driving unit causes a driving current, according to the light emission instruction signal, to flow through the semiconductor laser as the forward current thereof, the driving current being generated so as to control driving of the semiconductor laser with a current of the difference or sum with the control current of the negative feedback loop.

Abstract: A semiconductor device including a buffer layer 32 on n-GaAs, a clad layer 31, a wave guide layer 30 and a carrier block layer 29 of n-AlGaAs, a side barrier layer 28 of non-doped AlGaAs, an active layer 27 which is formed by two non-doped GaAs quantum well layers and a barrier layer of AlGaAs, a side barrier layer 26 of non-doped AlGaAs, a carrier block layer 25, a wave guide layer 23 and a clad layer 22 of p-AlGaAs, and a cap layer 21 of p-GaAs are grown in this order. Inside the wave guide layer 23, current blocking layers 24 having a lower refractive index and higher Al-composition than that of the wave guide layer and sandwich a strip-shaped active region 34. This creates a refractive index difference between the active region 34 and buried regions 33 in which each of the current blocking layers 24 exists, thereby forming a refractive index guide structure. Thus, it is possible to obtain a high-output semiconductor laser device of the refractive index guided type which is easy to manufacture.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: A semiconductor light emitting device of double hetero junction includes an active layer and clad layers. The clad layers include an n-type layer and p-type layer. The clad layers sandwich the active layer. A band gap energy of the clad layers is larger than that of the active layer. The band gap energy of the n-type clad layer is smaller than of the p-type clad layer.

Abstract: A laser resonator including a gain medium with strong thermal-lensing properties includes an arrangement for providing near real-time compensation for variations in the thermal-lensing effects in the gain-medium resulting from variations in resonator operating parameters.

Abstract: An optically-pumped laser having a small-molecule thin organic film of DCM doped Alq.sub.3. Carrier transport properties of the small-molecule organic materials, combined with a low lasing threshold provide a new generation of diode lasers employing organic thin films. An electrically-pumped variant is also described.

Abstract: The present invention provides another active layer structure provided in a light emission device for emitting a light with a predetermined wavelength. The active layer structure comprises a multiple quantum well structure and at least a second well layer. The multiple quantum well structure comprises alternating laminations of first well layers showing electroluminescence and potential barrier layers. The first well layers have a first set of energy band gaps which are uniform and corresponds to the predetermined wavelength, provided that energy band gap is defined as a difference between a ground level of electrons in conduction band and a ground level of holes in valence band. The second well layer is provided within any of the potential barer layers so that the second well layer is separated via the potential barrier layers from the first well layers.

Abstract: There is provided a small-diameter LD module which facilitates welding of a ferrule holder and a lens holder. An LD and a lens barrel having a lens press-fitted therein are supported by a lens holder, and a ferrule is supported by a ferrule holder. The diameter of the ferrule holder is set smaller than that of the lens holder. After the optical axes of the lens (and the LD) and an optical fiber are aligned, the lens holder and the ferrule holder are connected at welds, and then, the lens holder and a protective casing are connected at welds.

Abstract: A semiconductor laser includes a substrate of a first conductive type, a mesa provided on the substrate and having a multilayered structure including at least a cladding layer of the first conductive type, an active layer and another cladding layer of a second conductive type, a current blocking layer provided on both sides of the mesa, a buried layer of the second conductive type provided on the mesa and the current blocking layer, and a contact layer of the second conductive type provided in a predetermined region on the buried layer. The predetermined region does not include a portion immediately above the mesa.

Abstract: It is an object of the invention to provide a thinned semiconductor laser module.

Abstract: A broadband wavelength-selectable laser includes a gain medium, an optical transmission filter, and an optical fiber with a reflective filter such as a series of fiber Bragg gratings (FBGs). The gain medium is preferably a semiconductor laser diode that generates broadband optical energy. The gain medium is optically connected to the optical transmission filter, such as a bandpass filter, a notch filter, or a periodic filter, which converts the broadband optical energy into filtered optical energy having wavelength bands of high transmissivity and wavelength bands of low transmissivity. The optical transmission filter is optically connected to the series of FBGs that reflects different wavelength bands of optical energy. Either the optical transmission filter or the FBGs are tunable over a wavelength range that includes the desired laser wavelengths.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: In a semiconductor laser capable of changing its polarization mode, there are arranged a plurality of regions in its cavity direction and each region includes an active layer and a diffraction grating. The laser is driven by performing a control for switching the polarization mode to a region of the laser, out of the plurality of regions, where a refractive index is easier to be changed by a control than the other region.

Abstract: A method of fabricating an optical semiconductor device includes the steps of irradiating a substrate by a first optical beam and a second optical beam such that the first and second optical beams form interference fringes on the substrate, exposing a resist film provided on the substrate by the interference fringes to form a resist pattern, and forming a diffraction grating pattern on the substrate in accordance with the interference fringes by using the resist pattern as a mask. The first and second optical beams are irradiated such that a wavefront of the first optical beam and a wavefront of the second optical beam intersect at an intersection line parallel to the substrate, and the irradiating step is conducted by refracting the first and second optical beams by an optical element having a smooth surface inclined with respect to a plane parallel to the substrate in the direction of the foregoing intersection line and further inclined in a perpendicular direction.

Abstract: A semiconductor laser device comprises a mesa structure selectively grown on a InP substrate, the mesa structure having a laser active layer and an optical guide layer, current blocking layer disposed on both sides of the mesa structure and an embedding layer formed on the optical guide layer. Each of the current blocking layer and embedding layer has a refractive index lower than the refractive index of the optical guide layer. The selective growth of the mesa structure changes the thickness and width of the optical guide layer in the opposite directions to cancel the change in the lasing wavelength caused by fabrication errors.

Abstract: An AlGaInP/GaAs laser diode is disclosed in which the active region is made up of quantum wells that are sufficiently thin (less than 5 nm thick) that the transition energy increase due to quantum confinement of the carriers becomes significant. This allows the quantum well material composition to be selected for compressive strain so that the laser operates in the TE polarization mode, while still obtaining a transition energy of from 1.9-2.0 eV for 620-650 nm laser emission. Quantum barriers have sufficient thickness to confine carriers to the quantum wells. Self-pulsation may be obtained in a heterostructure that also includes a saturable absorption layer proximate to the active region and a ridge structure transversely confining absorption produced carriers in the central section of the absorber layer, while allowing lateral carrier diffusion to side regions where carriers are allowed to leave the absorber layer.