A problem with a conventional waveguide type laser device is that in the case in which an isotropic laser medium is used for a core, linearly polarized light is not provided. A ridge waveguide laser device of the present disclosure includes: a substrate; a core joined to the substrate and having a laser medium, the core having a refractive index higher than that of the substrate; and a cladding joined to the core, constituting a ridge waveguide together with the core, and made from a birefringent material having ordinary and extraordinary refractive indices lower than the refractive index of the core, the ordinary and extraordinary refractive indices being different.

A narrow linewidth external cavity semiconductor laser comprises semiconductor optical amplifier chip, comb-shaped optical filter, bandpass optical filter, partial reflection sheet, and collimated light beam coupling output assembly Collimated light beam coupling output assembly is composed of isolator, coupling lens, and output optical fiber. Laser resonant cavity is formed by partial reflection sheet and rear end face of semiconductor optical amplifier chip. Comb-shaped optical filter and bandpass optical filter form single-channel narrowband optical filtering assembly. Bandwidth enables laser to perform single-mode lasing and effectively restrain any other mode lasing. Longitudinal mode's relative position over whole filtering band may be controlled by adjusting laser temperature. Output wavelength and laser power are controlled and in best working state. Etalon is used as comb-shaped optical filter to easily realize narrow linewidth output. Commercial DWDM optical filter is used as bandpass optical filter to improve device wavelength flexibility and reduce costs.

An optical apparatus for depolarizing a laser beam within a fiber MOPA laser is disclosed. The apparatus includes a first phase modulator for spectral broadening, a linear polarizer, an optical coupler, a second phase modulator for depolarizing the laser beam, and a polarization-maintaining optical fiber. The optical coupler divides a linearly-polarized portion of the laser beam equally between fast and slow axes of the second phase modulator. The laser beam delivered by the polarization-maintaining optical fiber is truly unpolarized. The apparatus provides independent control of the spectral broadening and the depolarization to mitigate stimulated Brillouin scattering during subsequent amplification. A method for depolarizing a laser beam, using this apparatus, is also disclosed.

A laser light source unit for vehicles, with a resonator containing a first end mirror and a second end mirror, between which an active laser medium is arranged, and with a pump device for generating pump radiation, which can be introduced into the resonator via the first end mirror, wherein a rotatable birefringent medium is arranged in the resonator such that, according to a rotation of the birefringent medium, preferred radiation of different wavelengths is stimulated in the active laser medium.

A passively Q-switched solid-state laser includes a resonator (1) with an active laser material (2) and a decoupling end mirror (6) for decoupling laser pulses that have a pulse duration of less than 1 ns from the resonator (1), an optical fiber (13), into which the laser pulses decoupled from the decoupling end mirror (6) are injected, and a chirped volume Bragg grating (17), at which the laser pulses are reflected after they have passed through the optical fiber (13) for shortening the pulse duration. The pulse duration after the reflection on the chirped volume Bragg grating (17) is less than 30 ps. The active laser material (2) is Nd:YAG and a saturable absorber (3) that is formed from Cr:YAG and has a transmission in the unsaturated state of less than 50% is also arranged in the resonator. The length (a) of the resonator (1) is from 1 mm to 10 mm and the laser pulses decoupled at the decoupling end mirror (6) have a pulse energy from 1 J to 200 J.

A laser device for laser resonance ionization includes a wavelength variable grating-type titanium-doped sapphire laser and includes a titanium (Ti) doped titanium sapphire crystal disposed within a resonator. The titanium sapphire crystal is fixedly disposed on a stage. The titanium-doped sapphire crystal can be moved in the optical axis direction by the stage, thereby changing the position of the titanium-doped sapphire crystal. The switching between the wideband mode and the high-output mode can be performed by changing the position of the titanium-doped sapphire crystal.

An electro-optic modulator (EOM) for altering an optical path length of an optical field is described. The EOM comprises first and second Brewster-angle cut nonlinear crystals having a first and second optical axis. The optical axes are orientated relative to each other such that when an optical field propagates through the nonlinear crystals it experiences no overall deviation. The nonlinear crystals are also arranged to be opposite handed relative to the optical field. The EOM has the advantage that its optical losses are lower when compared with those EOMs known in the art. In addition, the EOM can be inserted into, or removed from, an optical system without any deviation being imparted onto the optical field. This reduces the levels of skill and effort required on the part of an operator. The described method and apparatus for mounting the nonlinear crystals also suppresses problematic piezo-electric resonances within the nonlinear crystals.

A wavelength selection method for a tunable laser includes: obtaining a target wavelength; and calculating target resistance values of two thermistors, respectively, corresponding to the target wavelength. Each of the two thermistors is used to monitor the temperature of a corresponding one of two wavelength selection components. Each of the target resistance values is calculated according to a relationship between a wavelength drift and a resistance change of the corresponding thermistor and according to an initial wavelength and an initial resistance value of the corresponding thermistor corresponding to the initial wavelength. The method further includes: heating the two wavelength selection components to control their temperatures until real-time resistance values of the two thermistors reach the target resistance values, respectively; and stabilizing the real-time resistance values at the target resistance values and outputting a laser beam having the target wavelength.

A laser apparatus includes: a laser chamber in which a pair of discharge electrodes is provided; a first beam expander configured to expand a beam width of a beam outputted from the laser chamber at least in a first direction substantially parallel to a direction of electric discharge between the discharge electrodes; and a line narrow optical system including: a second beam expander configured to expand a beam width of the beam outputted from the laser chamber at least in a second direction substantially perpendicular to the first direction, the second beam expander including at least one optical element; and a grating configured to perform wavelength dispersion of the beam expanded by the first and second beam expanders, the wavelength dispersion being performed in a plane substantially parallel to the second direction, wherein at least one of the grating and the at least one optical element is arranged so as to compensate for wavelength dispersion caused by the first beam expander.

A device may include a first photodetector to generate a first current based on an optical power of an optical beam. The device may include a beam splitter to split a portion of the optical beam into a first beam and a second beam. The device may include a wavelength filter to filter the first beam and the second beam. The wavelength filter may filter the second beam differently than the first beam based on a difference between an optical path length of the first beam and an optical path length of the second beam through the wavelength filter. The device may include second and third photodetectors to respectively receive, after the wavelength filter, the first beam and the second beam and to generate respective second currents.