Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Masao Imaki

Yoshihito Hirano

Yasuharu Koyata

Shigenori Shibue

Kouhei Teramoto

Kiyohide Sakai

Kenji Masuda

Shinichi Takagi

Yasunori Nishimura

Akihiro Adachi

Makoto Sato

Makoto Satou

Shinsuke Shikama

Jiro Suzuki

Syuhei Yamamoto

Takao Endou

Takeshi Nakamura

Takayuki Yanagisawa

Tetsuya Nishimura

Mitsunobu Gotoda

Yasunori Nisimura

Youhei Mikami

Yuji Masuyama

Provided is a device capable of oscillating a plurality of oscillation modes within a laser medium for obtaining a fundamental wave output which is easy in output scaling and high in luminance, thereby enabling a second harmonic conversion which is high in efficiency. The device includes: a laser medium () that is planar, has a waveguide structure in a thickness direction of a cross-section that is perpendicular to an optical axis (), and has a cyclic lens effect in a direction perpendicular to the optical axis () and the thickness direction; a clad () that is bonded onto one surface of the laser medium (); and heat sink () that is bonded onto one surface side of the laser medium () through the clad (), and in the device, a laser oscillation includes a laser oscillation that oscillates in a waveguide mode of the laser medium (), and a laser oscillation that oscillates in a plurality of resonator modes that are generated by a cyclic lens effect of the laser medium ().

Mode control waveguide laser device

A wavelength converting laser device includes a laser diode producing laser light and including an optical resonator having a pair of facing reflectors, including a reflecting surface having a shape reducing loss in the optical resonator, with regard to a specific horizontal transverse mode of laser light as compared to the loss in the optical resonator for other horizontal transverse modes, and a wavelength converter for converting the laser light into harmonic light.

Wavelength converting laser device

Provided are a speckle removing light source capable of removing speckle by using laser light whose wavelength is temporally changed and a lighting apparatus for producing an image from which the speckle is removed. Included are a light source for outputting laser light, and a light frequency modulator for temporally changing a wavelength of the laser light. The light frequency modulator has a predetermined period set for changing the wavelength of the laser light. Also, provided is a lighting apparatus, including a spatial light modulator illuminated with the laser light outputted from the speckle removing light source to produce an image. The spatial light modulator has a period set for producing the image, which is longer than the period for changing the wavelength of the laser light by the light frequency modulator.

Speckle removing light source and lighting apparatus

A reflection elementdisposed in an optical waveguide elementreturns a part of light to a semiconductor laser diode elementso that the semiconductor laser diode elementoscillates in a coherent collapse mode, and a semiconductor light amplifieris optically coupled to the optical waveguide element, and amplifies an optical output from optical waveguide element, so as to provide a high-power fundamental-wave light source.

Fundamental-wave light source and wavelength converter

Provided is a lighting apparatus capable of uniformly and efficiently lighting a spatial light modulator. The lighting apparatus includes: a light source for outputting laser light; a multimode optical fiber in which the laser light outputted from the light source propagates through an internal core whose lateral cross section is a substantially polygonal outer diameter shape; and spatial light modulator for producing an image with illumination light from the multimode optical fiber. In the lighting apparatus, the laser light is outputted from the light source and is propagated to the multimode optical fiber in which an outer diameter shape of the lateral cross section of the core is a substantially polygonal shape, whereby the spatial light modulator can be uniformly and efficiently lighted.

Lighting apparatus

An allowable temperature range satisfying phase matching conditions of a wavelength conversion device is widened. A wavelength conversion light source includes a semiconductor laser diode device () applied with an antireflection film (), a lens () arranged opposite to the semiconductor laser diode device (), an optical fiber () having a Bragg grating () arranged in a core thereof, and a wavelength conversion device () formed of a nonlinear optical crystal on which light from the semiconductor laser diode device () is incident. In the wavelength conversion light source, the semiconductor laser diode device () oscillates in coherent collapse mode.

Optical wavelength conversion light source

Wavelength conversion laser and image display

An optical signal emitted from a semiconductor laser is converged by a lens and then received by a single uniaxial birefringent crystal having a C axis that is inclined at an angle other than 90 degrees against a laser optical axis to output an optical signal having a polarized wave component of constant intensity corresponding to the wavelength of the optical signal regardless of temperature changes. The optical signal has an ordinary ray vibrating in a direction perpendicular to a plane including both the C axis and the laser optical axis, and an extraordinary ray vibrating in a direction perpendicular to both the ordinary ray and the laser optical axis. A first main photo detector detects the intensity of a p-polarized component of the optical signal that has passed through a polarizer and a second photo detector directly receives the optical signal converged by the lens.

Wavelength monitoring apparatus

A wavelength filter includes a solid material that is optically transparent and including a pair of planar surfaces substantially parallel to each other; and a supporting member that supports the solid material on a planar surface of the solid material other than the pair of planar surfaces, the supporting member having a rigidity higher than that of the solid material. The solid material is a birefringent material of which an optical axis makes a predetermined angle with respect to a normal to the pair of planar surfaces, and the wavelength filter selects light having a wavelength that is determined by an optical length between the pair of planar surfaces by resonating the light between the pair of planar surfaces.

Wavelength filter and wavelength monitor device

On a plate of birefringent crystal made of an LiNbOcrystal or an LiTaOcrystal, a conductive substance is adhered to the whole periphery of side surfaces of the plate that intersect an incident surface of a laser beam, thereby to form a wave plate. A polarizer is provided at the latter stage of the wave plate. A wavelength is monitored based on an output from the polarizer. With this arrangement, based on the use of the LiNbOcrystal or the LiTaOcrystal that can be manufactured by a large quantity at low cost, it is possible to obtain polarization characteristics and wavelength discrimination characteristics that are stable against environmental changes such as temperature and external stress, by suppressing the pyroelectric effect and the piezoelectric effect of these materials.

Wave length plate, wavelength filter and wavelength monitor

An oscillation state of a semiconductor laser is decided. Injection current to the first and second light reflectors of the semiconductor laser are simultaneously swept based on the oscillation state of the semiconductor laser to obtain current conditions of the injection current to the first and second light reflectors that carry out single-mode oscillation in a target wavelength. The semiconductor laser is drive controlled with the obtained current conditions.

Method of and apparatus for controlling wavelength variable semiconductor laser without preparing a high-precision current table

A wavelength monitor comprises a cylindrical lens configured to allow a laser beam emitted from a semiconductor laser to pass therethrough, first and second photodetectors configured to receive the laser beam through the cylindrical lens, and a wavelength filter disposed in an optical path between the semiconductor laser and the first photodetector.

Wavelength monitor and semiconductor laser device

A backward laser beam radiated from a laser diode is received in a photo diode, and an intensity of a forward laser beam radiated from the laser diode is adjusted according to the intensity of the received backward laser beam. The forward laser beam radiated from the laser diode is collimated in a first lens held by a lens holder, and a most portion of the forward laser beam is output through a package window inclined with respect to an optical axis of the laser diode. The remaining portion of the forward laser beam is reflected on the package window as a reflected laser beam and is transmitted through the first lens to be converged in a narrow area placed above the laser diode. A light shielding plate extending in a plane orthogonal to the optical axis is arranged in a wide area including the narrow area and shields the photo diode from the reflected laser beam from. Therefore, the intensity of the forward laser beam radiated from the laser diode is correctly adjusted. Also, the light shielding plate is not soldered to the laser diode but is fixed to lens fixing posts arranged to support the lens holder. Therefore, a driving current can be supplied to the laser diode through a bonding wire without being influenced by the light shielding plate.

Semiconductor laser device for optical communication

A wavelength monitoring device comprising: a polarization state changing means having a first birefringent crystal, which inputs a polarized laser light and changes the polarization state of the input laser light after it is transmitted through the first birefringent crystal, in accordance with the wavelength of the input laser light, a polarized light selecting and receiving means, which inputs the laser light transmitted through the polarization state changing means and selectively receives a predetermined linearly polarized component, and a wavelength detection means for monitoring the wavelength of the laser light input to the first birefringent crystal by use of an optical signal output from the polarized light selecting and receiving means.

Wavelength monitoring device and its adjusting method, and wavelength stabilizing light source and transmission system having plural wavelength stabilizing light source

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Tokyo, Japan

Masao Imaki