Abstract: Spot-size conversion for interfacing a first optical element having a higher refractive index to a second optical element having a lower refractive index is achieved through the use of two optical star couplers coupled to each other through a plurality of optical paths embedded in a planar waveguide. The beam from the high refractive index element is introduced into a high numerical aperture (NA) star coupler, which directs the beam through a plurality of optical paths to a second star coupler with a lower numerical aperture than the first star coupler so that its output spot-size is larger. The output port of the second star coupler is interfaced to the lower refractive index element. Wavelength selection can be provided by making non-zero path-length differences between adjacent optical paths between the two star couplers.

Abstract: The width of a current pass region of a semiconductor laser device is narrowed as much as possible, thus implementing a stable single transverse mode. The device is relatively resistant against physical impact. The device includes a semiconductor substrate having first and second opposite surfaces, and, in order, a first conductive type clad, active layer, etch stop layer, current blocking layer formed in a V-groove shape so that a part of the etch stop layer is exposed, second conductive type clad formed entirely over the entire of the V-groove and the current blocking layer, optical guide layer, current pass facilitation layer, cap layer, second conductive type electrode, and a first conductive type electrode formed on the second surface of the semiconductor substrate.

Abstract: A 780 nm band semiconductor laser device has an InGaAsP well layer, phosphorous composition of which is 0.51 smaller than 0.55 to prevent spinodal decomposition in growing InGaAsP. A compressive strain of 0.65% less than 1% and more than 0.25% is introduced into the well layer to reduce threshold current thereof. Thus, the 0.78-?m band semiconductor laser device having the InGaAsP well layer stably operates for a long time even in outputting a high optical power of 100 mW or more. A tensile strain of 1.2% is also introduced into barrier layers within the active region so as to compensate the stress due to the compressive strain of the well layer. As a result, the reliability of the semiconductor laser device is further increased during a high output operation.

Abstract: Our wafer scale processing techniques produce chip-laser-diodes with a diffraction grating (78) that redirects output light out the top (88) and/or bottom surfaces. Generally, a diffraction grating (78) and integrated lens-grating (78) are used herein to couple light from the chip to an output fiber (74), and the lens-grating (78) is spaced from the diffraction grating (76). Preferably the diffraction grating (76) and integrated lens grating (78) are also used to couple light from the output fiber (74) back to the active region of the chip. The integrated lens-grating (78) can be in a coupling block (82). The use of a coupling block (82) can eliminate “facet-type damage”. A coupling block (82) is generally used herein to couple light from the chip to an output fiber (74), and preferably to couple feedback reflected from the fiber (74) back to the chip.

Abstract: A high power driver system has a predetermined number of driver modules for driving a high power device such as a laser-emitting device. Each driver module has a driver circuit and a corresponding feedback circuit. The driver circuits respectively generate driving currents, and then the driving currents are collected to drive the high power laser-emitting device or other high power devices. In addition, these feedback circuits of the driver modules receive the same detection signal that represents the output power of the high power laser-emitting device. Then, each feedback circuit responds to the same detection signal to generate a feedback signal, respectively, which makes the corresponding driver circuit carry out a feedback action for adjusting the driving currents.

Abstract: A method for stabilizing a laser frequency using sub-Doppler spectral spectrum of atoms, and a laser frequency stabilization device used in the method which is comprised of a gas charged cell, a laser, a laser frequency adjusting means, a laser beam dividing means for dividing the laser beam into a pump beam and a probe beam, a photo detector for measuring intensity of the probe beam after passed through the cell, an ON/OFF means for cutting off the pumping beam at a constant time interval, a computing means for obtaining the intensity of the probe beam, a demodulated signal of the probe beam, the difference in intensity between the probe and pumping beam, and a difference in demodulated signal, and a feedback means which feeds back the information to the laser frequency adjusting means, thereby stabilizing the frequency of the laser.

Abstract: The invention relates to a semiconductor laser of the surface emitting type. In order to provide a semiconductor laser which can be operated at normal ambient temperatures and has stable long-term characteristics, the semiconductor laser comprises an active zone having a pn transition, a first n-doped semiconductor layer on the n side of the active zone, a structured tunnel contact on the p side of the active zone, which forms a conductive transition to a second n-doped semiconductor layer on the p-side of the active zone, a structured dielectric mirror, which is applied to the second n-doped semiconductor layer, a contact layer, which forms a contact with the second n-doped semiconductor layer at the places where the dielectric mirror is not applied, and a diffusion barrier between the contact layer and the second n-doped semiconductor layer.

Abstract: A wavelength conversion apparatus in which output direction of a wavelength-converted laser beam, having a wavelength converted by a nonlinear optical crystal and emitted through an output-window, can be brought close to the direction of optical axis of the laser beam passing through the nonlinear optical crystal. In addition, axial deviation of the wavelength-converted laser beam converted by the nonlinear optical crystal and emitted through an output-window, can be reduced when the position of the nonlinear optical crystal is moved. The output facet of the nonlinear optical crystal is inclined at Brewster's angle with respect to the wavelength-converted laser beam. An output-window of a case containing the nonlinear optical crystal has a prism form in which the distance between a laser beam input facet and a laser beam output facet of the output-window is reduced along a direction in which the wavelength-converted laser beam, emitted from the nonlinear optical crystal, inclines.

Abstract: Resonant cavity diode, operating at the same wavelength for emission and detection of light. This diode is particularly applicable to telecommunications and comprises a resonant cavity (12) delimited by two mirrors (8, 16) and containing an active medium (14) and at least two insulating and coaxial rings (24, 30, 32) with the same inside diameter and the same outside diameter, the total thickness of the rings being provided such that the optical length of the resonant cavity is k×? (k?2), in the part of this cavity that passes through the rings, and is (k?1)×? in the part containing these rings, where ? is the wavelength at which the diode is capable of emitting and detecting.

Abstract: A gas discharge laser crystallization apparatus and method for performing a transformation of a crystal makeup or orientation in the substrate of a workpiece is disclosed which may comprise, a multichamber laser system comprising, a first laser unit comprising, a first and second gas discharge chamber; each with a pair of elongated spaced apart opposing electrodes contained within the chamber, forming an elongated gas discharge region; a laser gas contained within the chamber comprising a halogen and a noble gas selected to produce laser light at a center wavelength optimized to the crystallization process to be earned out on the workpiece; a power supply module comprising, a DC power source; a first and a second pulse compression and voltage step up circuit connected to the DC power source and connected to the respective electrodes, comprising a multistage fractional step up transformer having a plurality of primary windings connected in series and a single secondary winding passing through each of the plura

Abstract: The invention relates to a method for checking the regulation state of a frequency-stabilised laser system comprising a laser (2). At least one first sidebrand frequency VHF is modulated to the laser beam (1) of said laser, the laser beam being guided through an absorption material (13) comprising a plurality of absorption lines in a detuning region of the laser (2), said absorption lines being arranged at different distances from each other. The laser frequency VL is detuned and, as a regulation signal for the laser frequency VL, it is determined whether there has been an absorption in the absorption material.

Abstract: A semiconductor laser device have, on a substrate, a semiconductor layer including an active layer sandwiched between an n-type layer and a p-type layer, the semiconductor layer having a sonator face formed by etching and a projection projecting out in an emission direction relatively to the resonator face, wherein a protective film is formed to extend from the resonator face to an end face of the projection, and, an emission critical angle, which is the largest angle at which light emitted from the resonator face can be radiated without being blocked by the projection and the protective film formed on the projection, is larger than an emission half-angle of an emission distribution in a vertical direction of a laser beam emitted from the resonator face.

Abstract: A one dimension all-metal slab waveguide gas laser comprises a slab waveguide gas discharge area and an optical resonator disposed in a metal vacuum chamber. The gas discharge area is formed by a top and a bottom metal electrodes and metal supporting blocks insolated with the electrodes. A metal liner plate and a metal press plate are sequentially disposed on upside of the metal electrodes. A metal supporting plate is disposed at underside of the metal electrodes. The metal top electrodes are connected with a supply power through link pins of the metal electrodes. An output mirror and a feedback mirror are respectively arranged at two sides of the optical resonator. An output window of the laser is disposed in the vacuum chamber.

Abstract: An integrated optical parametric oscillator, having an optical parametric oscillation region to convert a pump source into a signal beam and an idler beam, and a fine-steering region to adjust optical path of the signal beam in order to finely select a required wavelength component of the signal beam. The optical parametric oscillator is contoured with a plurality of exterior planes with specific reflective characteristics to form a resonator of the idler beam while reflecting and diffracting the signal beam with a desired wavelength.