Abstract: A design of a semiconductor saturable absorber that offers a convenient and reliable way to control/decrease the recovery time of the absorption. The absorption recovery time is controlled during the epitaxial growth by using lattice-mismatched layer(s) to induce dislocations, and implicitly non-radiative recombination centers within the nonlinear absorbing region. These lattice reformation layer(s) are interposed between the distributed Bragg reflector and the nonlinear absorption region, containing quantum-wells, quantum-dots or bulk semiconductor material. The thickness and composition of the lattice reformation layer(s) is an instrumental to control the amount of non-radiative recombination centers used to trap the optically excited carriers generated in the absorption region.

Abstract: Semiconductor laser diodes, particularly high power ridge waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement concerns a method of suppressing the undesired first and higher order modes of the laser which consume energy and do not contribute to the optical output of the laser, thus reducing it's efficiency. This novel effect is provided by a structure comprising CIG—for Complex Index Guiding—elements on top of the laser diode, said CIG being established by fabricating CIG elements consisting of one or a plurality of layers and containing at least one layer which provides the optical absorption of undesired modes of the lasing wavelength.

Abstract: A method for fabricating a semiconductor light-emitting element according to the present invention includes the steps of (A) providing a striped masking layer on a first Group III-V compound semiconductor, (B) selectively growing a second Group III-V compound semiconductor over the entire surface of the first Group III-V compound semiconductor except a portion covered with the masking layer, thereby forming a current confining layer that has a striped opening defined by the masking layer, (C) selectively removing the masking layer, and (D) growing a third Group III-V compound semiconductor to cover the surface of the first Group III-V compound semiconductor, which is exposed through the striped opening, and the surface of the current confining layer.

Abstract: A semiconductor saturable absorber and the fabrication method thereof are provided. The semiconductor saturable absorber includes a Fe-doped InP substrate, a periodic unit comprising an AlGaInAs QW formed on the Fe-doped InP substrate and an InAlAs barrier layer formed on one side of the AlGaInAs QW, and another InAlAs barrier layer formed on the other side of the AlGaInAs QW. Each of the InAlAs barrier layers has a width being a half-wavelength of a light emitted by the AlGaInAs QW.

Abstract: In a semiconductor laser device of the invention, a ridge portion 150 forms a waveguide, and guided light goes along the ridge portion 150. A tail of the guided layer is present also at first side portions 151, while second side portions 152 are regions which the tail of the guided light does not reach. Meanwhile, scattered light generated from the ridge portion 150 goes through the first side portions 15, spreading into the second side portions 152. In the second side portions 152, a light absorption layer 127 serving as a light absorber is formed on the first upper clad layer 108, where the scattered light is absorbed. As a result of the absorption of scattered light in the second side portions 152, ripples of radiation light are reduced. Also since the light absorption layer 127 is in electrical contact with a p-side ohmic electrode 125, the problem of charge accumulation to the light absorption layer 127 can be avoided.

Abstract: A semiconductor laser device has an active layer which is divided into two regions in the direction of a resonator, i.e., a light-amplifying region and a saturable absorber region. The light-amplifying region and the saturable absorber region are produced to allow the semiconductor laser device to be in a bistable state. For the light-amplifying region and the saturable absorber region respectively, p-electrodes are separately and independently formed. N-electrodes are provided in relation to the p-electrodes. From one of the p-electrodes, a current which is modulated with noise added thereto is injected.

Abstract: A nitride-based semiconductor laser device capable of elongating the life thereof is obtained. This nitride-based semiconductor laser device comprises a first cladding layer consisting of a first conductivity type nitride-based semiconductor, an emission layer, formed on the first cladding layer, consisting of a nitride-based semiconductor and a second cladding layer, formed on the emission layer, consisting of a second conductivity type nitride-based semiconductor, while the emission layer includes an active layer emitting light, a light guiding layer for confining light and a carrier blocking layer, arranged between the active layer and the light guiding layer, having a larger band gap than the light guiding layer.

Abstract: A semiconductor laser diode device with small driving current and no distortion in the projected image.

Abstract: A light emitting device comprises a waveguide having an electrically pumped gain region, a nonlinear medium, and an inclined mirror. Light pulses emitted from the gain region are reflected by the inclined mirror into the nonlinear medium in order to generate frequency-doubled light pulses. The gain region and the inclined mirror are implemented on the same substrate. The resulting structure is stable and compact, and allows on-wafer testing of produced emitters. The folded structure allows easy alignment of the nonlinear crystal.

Abstract: In a vertical cavity surface-emitting semiconductor laser device, first and second resonance wavelengths which are different are provided while a first resonator and a second resonator are coupled optically, and a gain of an active layer at the first resonance wavelength on the side of short wavelength is higher than that at the second resonance wavelength on the side of long wavelength. An absorption coefficient of an optical absorption layer when no electric field is applied is small for the first and second resonance wavelengths, and when an electric field is applied, an absorption coefficient of the optical absorption layer for the first resonance wavelength on the side of short wavelength is larger than that for the second resonance wavelength on the side of long wavelength.

Abstract: A semiconductor laser device includes a MQW active layer, a p-type cladding layer formed on the MQW active layer, having a ridge portion and having a smaller refractive index than that of the MQW active layer, a plurality of dielectric films formed at least on part of the p-type cladding layer extending from each side of the ridge portion.

Abstract: A VCSEL is provided that integrates an absorbing layer sandwiched within a null of the standing wave in the emitting mirror to reduce the reflectivity and transmissivity of the emitting mirror as seen by the feedback optical wave, with minimal effect on the reflectivity of the emitting mirror as seen by the light exiting the cavity. The absorbing layer may be made of a suitable absorbing material, such as a GaAs layer in a laser emitting near 850 nm or highly doped p-layer, for instance, and may be disposed epitaxially in a semiconductor or metamorphic mirror. The absorbing layer sandwich may be incorporated into the VCSEL after the last mirror pair or at any desired position with the emitting mirror array.

Abstract: The present invention provides a semiconductor laser diode that has the buried mesa stripe and a current blocking layer without involving any pn-junction. The laser diode includes a lower cladding layer, an active region and an upper cladding layer on the GaAs substrate in this order. The mesa stripe, buried with the current blocking layer, includes the first portion of the upper cladding layer in addition to the active region. The current blocking layer of the invention is made of one of un-doped GaInP and un-doped AlGaInP grown at a relatively low temperature below 600° C. and shows high resistivity greater than 105 ?·cm for the bias voltage below 5 V.

Abstract: A self-pulsating semiconductor laser includes a lower clad layer formed on a semiconductor substrate, an active layer formed on the lower clad layer, the first upper clad layer formed on the active layer, a second upper clad layer formed on the first upper clad layer and a block layers. The second upper clad layer has a mesa structure. The block layers are formed on both sides of the second upper clad layer and includes a layer the bandgap thereof is larger than that of the active layer. When a self-pulsation is performed, saturable absorber regions are formed on the both sides of a gain region. The thickness d of the first upper clad layer satisfies a relation 220 nm?d?450 nm. A stable self-pulsation can be achieved in a wide temperature range.

Abstract: A semiconductor device comprises an active region (4), a cladding layer (5,7), and a saturable absorbing layer (6) disposed within the cladding layer. The saturable absorbing layer comprises at least one portion (11a) that is absorbing for light emitted by the active region and comprises at least portion (11b) that is not absorbing for light emitted by the active region. The fabrication method of the invention enables the non-absorbing portion(s) (11b) of the saturable absorbing layer (6) to produced after the device structure has been fabricated. This allows the degree of overlap between the non-absorbing portion(s) (11b) of the saturable absorbing layer (6) and the optical mode of the laser to be altered after the device has been grown.

Abstract: A semiconductor device comprises an active region (4), a cladding layer (5,7), and a saturable absorbing layer (6) disposed within the cladding layer. The saturable absorbing layer comprises at least one portion (11a) that is absorbing for light emitted by the active region and comprises at least portion (11b) that is not absorbing for light emitted by the active region. The fabrication method of the invention enables the non-absorbing portion(s) (11b) of the saturable absorbing layer (6) to produced after the device structure has been fabricated. This allows the degree of overlap between the non-absorbing portion(s) (11b) of the saturable absorbing layer (6) and the optical mode of the laser to be altered after the device has been grown.

Abstract: A semiconductor laser, contains at least one absorbing layer (8) in its laser resonator, said absorbing layer reducing the transmission TRes of the laser radiation (10) in the laser resonator for the purpose of decreasing the sensitivity of the semiconductor laser to disturbances created by radiation (9) fed back into the laser resonator. This reduces fluctuations in the output power due to fed-back radiation (9).

Abstract: An optical AND element includes a semiconductor laser having a plurality of saturable absorption regions on an optical waveguide, electrodes of the saturable absorption regions being separated from each other, and a light inputting section for inputting light into the respective saturable absorption regions.

Abstract: A mode-locked integrated semiconductor laser has a gain section and an absorption section that are based on quantum-confined active regions. The optical mode(s) in each section can be modeled as occupying a certain cross-sectional area, referred to as the mode cross-section. The mode cross-section in the absorber section is larger in area than the mode cross-section in the gain section, thus reducing the optical power density in the absorber section relative to the gain section. This, in turn, delays saturation of the absorber section until higher optical powers, thus increasing the peak power output of the laser.

Abstract: A semiconductor laser diode capable of achieving an improvement in kink level and an improvement in catastrophic optical damage (COD) level. The semiconductor laser diode includes a first-conductivity type semiconductor substrate, a first-conductivity type clad layer formed over the substrate, an active layer formed over the first-conductivity type clad layer, a second-conductivity type clad layer formed over the active layer, and provided with a ridge, and a light confining layer formed on the second-conductivity type clad layer, and made of a first-conductivity type semiconductor material, the light confining layer including higher-order mode absorption layers having an energy band gap lower than optical energy produced in the active layer, and refractive index control layers having a refractive index lower than that of the higher-order mode absorption layers. The higher-order mode absorption layers and refractive index control layers are laminated in an alternate manner.

Abstract: A semiconductor laser device includes: a first cladding layer, which is made of a nitride semiconductor of a first conductivity type and is formed over a substrate; an active layer, which is made of another nitride semiconductor and is formed over the first cladding layer; and a second cladding layer, which is made of still another nitride semiconductor of a second conductivity type and is formed over the active layer. A spontaneous-emission-absorbing layer, which is made of yet another nitride semiconductor of the first conductivity type and has such an energy gap as absorbing spontaneous emission that has been radiated from the active layer, is formed between the substrate and the first cladding layer.

Abstract: A modelocked linear fiber laser cavity with enhanced pulse-width control includes concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers are included in the cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth are obtained by matching the dispersion value of the fiber Bragg grating to the inverse of the dispersion of the intra-cavity fiber.