Abstract: A semiconductor laser drive device includes a semiconductor-laser drive element to generate a drive current according to an input control signal to supply the drive current to a semiconductor laser, a control circuit to control the drive current by controlling the semiconductor-laser drive element, and a drive current detection circuit to detect a current value of the drive current supplied to the semiconductor laser and generate a digital control signal representing the detected digital value of the drive current to output.

Abstract: A semiconductor laser has a first diffractive grating area. The first diffractive grating area has a plurality of segments. Each segment has a first area including a diffractive grating and a second area that is space area combined to the first area. Optical lengths of at least two of the second areas are different from each other. A refractive-index of each of the segments are changeable.

Abstract: The invention relates to a method for the production of a photon pair source, which generates entangled photon pairs, having at least one quantum dot, wherein in the method the operational behaviour of the photon pair source is determined by adjusting the fine structure splitting of the excitonic energy level of the at least one quantum dot. It is provided according to the invention for the fine structure splitting of the excitonic energy level to be adjusted by depositing the at least one quantum dot on a {111} crystal surface of a semiconductor substrate.

Abstract: An optically pumped laser oscillator or amplifier including a laser head including a gain medium exhibiting polarization-dependent absorption along two crystallographic axes and a pump source producing a pump beam. The medium's absorption coefficients along both of the crystallographic axes are equal or the difference between the absorption coefficients relative to the lowest absorption coefficients is reduced at least by a factor of two compared to the same relative difference between the two absorption coefficients at the medium's absorption peaks. In some embodiments, the gain medium is a crystal, e.g., a Neodymium-doped Vanadate (Nd:YVO4) crystal, greater than 15 mm. In various embodiments, the optically pumped laser oscillator or amplifier includes two pump sources producing two pump beams.

Abstract: The different advantageous embodiments provide an apparatus and method comprising a substrate configured to increase an intensity of light at a desired wavelength. The substrate has a front side, a back side, and an outer edge. The substrate is configured to reflect the light received on the front side of the substrate. The substrate comprises ceramic. The substrate comprises a plurality of sections. The method and apparatus also comprise a material configured to attenuate the light passing between the plurality of sections. The material surrounds an edge of each section of the plurality of sections. The apparatus and method also comprise a cooling system configured to allow liquid nitrogen to be transmitted through the cooling system and receive heat generated in the substrate from the back side of the substrate.

Abstract: This invention relates to semiconductor laser apparatus with a structure for reducing the divergence angle of output light and for narrowing the spectral width. The semiconductor laser apparatus has at least a semiconductor laser array, a collimator lens, a path rotator, and an optical element with a reflecting function. The collimator lens collimates a plurality of laser beams from the semiconductor laser array, in a predetermined direction. The path rotator outputs each beam collimated in the predetermined direction, with a predetermined divergence angle in the predetermined direction in a state in which a transverse section of the beam is rotated by about 90°. The optical element is arranged at a position where at least a part of each beam from the path rotator arrives, and constitutes at least a part of an external resonator. This optical element reflects a part of each beam from the path rotator to return the reflected part of each beam to the active layer in the semiconductor laser array.

Abstract: [Task] To provide a semiconductor light emitting element capable of emitting light beams with wavelengths in a plurality of wavelength ranges with a high optical output, a driving method of a semiconductor light emitting element capable of making a semiconductor light emitting element that can emit light beams with wavelengths in a plurality of wavelength ranges operate with a high optical output, a light emitting device, and a small and high-performance optical pulse tester using the light emitting device. [Means for Resolution] In a driving method of a semiconductor light emitting element with a configuration in which an active layer 13a with a gain wavelength ?1 of about 1.55 ?m and an active layer 13b with a gain wavelength ?2 of about 1.

Abstract: Provided is a semiconductor laser device that is free from or suffers less from deterioration resulting from a surge or that is less likely to suffer from deterioration resulting from a surge. The semiconductor laser device has a conductive stem 101, a submount 102 fixed to the stem 101, a nitride semiconductor laser chip 103 mounted on the submount 102, pins 104 and 105 fixed to the stem 101 but insulated therefrom, a wire connecting the pin 104 to a p-electrode of the nitride semiconductor laser chip 103, a wire connecting the pin 105 to an n-electrode of the nitride semiconductor laser chip 103, and a cap 106 enclosing the nitride semiconductor laser chip 103 and the submount 102 and fixed to the stem 101.

Abstract: A laser device with frequency conversion, the device comprising a complex optical cavity comprising two cavity parts with two different levels of circulating intracavity power wherein there is placed at least one non-linear crystal (30) is placed within the cavity part of higher circulating power and an active medium (21) in the cavity part of lower circulating power, the power enhancement achieved in two steps and the total enhancement being the product of the enhancement factors in each step, providing additional freedom in design allowing both the condition for high enhancement of the interacting laser power inside the intracavity non-linear crystal and the condition for maximum power output from the laser to be satisfied simultaneously and wherein said complex optical cavity the first cavity part provides the initial step of power enhancement and comprises at least a laser cavity back mirror (20), highly reflective about a laser radiation fundamental frequency .omega., and an active (gain) medium.

Abstract: An LD with an improved heat dissipating function in the edge regions is disclosed. The LD provides the core region including the active layer and extending whole of the substrate, and the ridge waveguide structure on the core region that extends in a direction along which the light generated in the active layer is guided. The ridge waveguide structure is buried by a thick resin layer in both sides thereof, but the resin layer is removed in the edge regions close to respective facets of the LD.

Abstract: An optical semiconductor device has a semiconductor substrate, a semiconductor region and heater. The semiconductor region has a stripe shape demarcated with a top face and a side face thereof. The stripe shape has a width smaller than a width of the semiconductor substrate. An optical waveguide layer is located in the semiconductor region. A distance from a lower end of the side face of the semiconductor region to the optical waveguide layer is more than half of the width of the semiconductor region. The heater is provided above the optical waveguide layer.

Abstract: A solid-state suspension laser. The novel laser includes a gain medium comprised of a plurality of solid-state gain particles suspended in a fluid. The laser also includes a pump source for pumping the gain particles and a resonator for amplifying and outputting laser light generated by the gain medium. In an illustrative embodiment, the gain medium is adapted to flow, and the pumping of the gain medium occurs outside of the resonator. The flow velocities and the densities of the gain particles in the gain medium can be optimized for optimal absorption efficiency during the pumping and/or for optimal extraction efficiency in the resonator as well as for overall laser performance optimization, including power, efficiency and beam quality scalability.

Abstract: In a semiconductor optical device, the first conductive type semiconductor region includes a first semiconductor portion and a second semiconductor portion. The first and second regions of the first semiconductor portion are arranged along a predetermined plane. The second semiconductor portion is provided on the first region of the first semiconductor portion. The active layer is provided on the second semiconductor portion of the first conductive type semiconductor region. The second conductive type semiconductor region is provided on the second region of the first semiconductor portion of the first conductive type semiconductor region. The side of the second semiconductor portion of the first conductive type semiconductor region, the top and side of the active layer, the second region of the first conductive type semiconductor region and the second conductive type semiconductor region constitute a pn junction.

Abstract: To provide surface-emitting type semiconductor lasers and methods of manufacturing the same in which the polarization direction of laser light can be readily controlled, a surface-emitting type semiconductor laser includes a vertical resonator above a substrate. The vertical resonator includes a first mirror, an active layer and a second mirror disposed in this order from the substrate. The vertical resonator has a plurality of unit resonators. An emission region of each of the unit resonators has a diameter that oscillates in a single-mode.

Abstract: One facet of a nitride based semiconductor laser device is composed of a cleavage plane of (0001), and the other facet thereof is composed of a cleavage plane of (000 1). Thus, the one facet and the other facet are respectively a Ga polar plane and an N polar plane. A portion of the one facet and a portion of the other facet, which are positioned in an optical waveguide, constitute a pair of cavity facets. A first protective film including nitrogen as a constituent element is formed on the one facet. A second protective film including oxygen as a constituent element is formed on the other facet.

Abstract: Two-dimensional photonic crystal surface-emitting laser comprising a two-dimensional photonic crystal, having media different in refractive index arrayed in a two-dimensional cycle, disposed in the vicinity of an active layer that emits light by the injection of carriers, wherein the two-dimensional photonic crystal consists of square lattices having equal lattice constants in perpendicular directions, and a basic lattice consisting of a square with one medium as a vertex has an asymmetric refractive index distribution with respect to either one of the two diagonals of the basic lattice to thereby emit light in a constant polarizing direction.

Abstract: Semiconductor lasers are driven such that high output laser beams are stably obtained without a long start up time. The light outputs of a plurality of semiconductor lasers are detected by photodetectors. The semiconductor lasers are driven by automatic power control based on comparison results between the output of the photodetectors and a set value corresponding to a target light output for the semiconductor lasers. A correction pattern that corrects the set value and/or the output of the photodetectors such that the actual light output becomes uniform is generated in advance. The set value and/or the output are varied according to the correction pattern for a predetermined period of time from initiation of drive. A single correction pattern is employed in common with respect to the plurality of semiconductor lasers.

Abstract: A laser system according to the invention comprises pump generating means (x02, x03) for generating at least a first and a second, preferably focused, pump beam, and lasing means (x06, x07) for emitting radiation by being appropriately pumped. The lasing means (x06, x07) is disposed in a first resonator so as to receive the first pump beam in order to generate a first beam (x21) having a first frequency, and the lasing means (x06, x07) is disposed in a second resonator so as to receive the second pump beam in order to generate a second beam (x22) having a second frequency. At least one Q-switch (x08; x17, x18) is disposed in the first and the second resonator, so that the first beam and the second beam both pass a Q-switch (x08; x17, x18). The laser system (x01) has an output (x13) generated from said first beam (x21) and said second beam (x22), and at least a part of said output (x13) is fed back to a regulation system (x14), said regulation system (x14) controlling said pump generating means (x02, x03).

Abstract: A method to stabilize the repetition rate in a passive harmonic mode-locked fiber laser employing semiconductor saturable absorbers. The pulse organization is accomplished by electrically modulating the amplifier pump source that in turn optically modulates the saturable loss of semiconductor absorber. Due to an efficient modulation mechanism of the cavity loss, the method can be used to generate an actively mode-lock pulse train.

Abstract: A surface emitting laser comprises an underlayer, an active layer formed on the underlayer, a slab layer formed on the active layer and having a photonic crystal structure optically combined with the active layer, and a metal thin film formed on the slab layer and having a periodic fine structure; and enabling taking-out of the light beam propagating in a layer-plane direction in the slab layer through the metal thin film.