Pioneer Electronic Corporation

Sumitomo Electric Industries, Limited

Sota Okamoto

Kiyofumi Chikuma

Takafumi Uemiya

Yasuhiro Hattori

Akira Mizoguchi

Naota Uenishi

Teruo Tohma

Yasuji Ogaki

An optical pickup using a fiber type SHG, an optical information recording carrier and an information recording and reproducing apparatus. In the optical pickup, the primary ray which was removed in conventional arrangements is utilized thereby the same pickup can be used not only for an optical disk of a high density but also for an optical disk of a usual record density. To raise the recording density of the information recording carrier the laminated structure is utilized to record information. Two rays having different wavelengths are directed onto the record layer and onto the recordable layer of the optical disk, and the information recording and reproducing apparatus performs the reproducing of information as well as error detection and record/reproduction of information, so that a novel reproduction mode is realized.

Optical pickup, optical information recording carrier and recording and

A fiber type optical wavelength converter has a core made of nonlinear optical crystal and a clad surrounding the core. The core and clad have an effective refractive index N.sup..omega. satisfying the following inequality

Fiber type wavelength converter

A wavelength converting device is constructed by: a fiber type wavelength converting device which uses the Cerenkov radiation type phase matching and comprises a non-linear optical crystalline core and a clad; and a transparent resin portion surrounding the wavelength converting device, wherein the resin portion has a resin outgoing edge surface of a large enough size such that the entire second harmonics light is emitted from the outgoing edge surface. The above device is a light-wavelength converting device having long enough operation length and a high conversion efficiency and is a device having an excellent environmental resistance and a high coupling efficiency.

Wavelength converting device having a surrounding resin layer

A stable wavelength converting apparatus comprising an axicon having a convex conical surface on that side where a second harmonics enters and a concave conical surface on the light-leaving side. This design feature can reduce the deviation of the collimation by the axicon.

Laser wavelength converter

The optical wavelength conversion device according to the present invention comprises a light source for emitting a fundamental wave, a waveguide type optical wavelength conversion element having an optical coupler to receive said fundamental wave and an optical waveguide made of non-linear optical material for converting the fundamental wave to a secondary harmonic, and a light-focused optical system having an objective lens for converging the fundamental wave to the optical coupler, wherein the light-focused optical system includes an optical tilting means for tilting the optical axis of the fundamental wave with respect to the optical axis of the objective lens. The wavelength conversion device having a simple arrangement of an optical system can guide the fundamental wave to the wavelength conversion element at a high accuracy.

Optical wavelength conversion device with high alignment accuracy

As the wavelength conversion element is built by jointing a first clad member having a groove section filled with organic non-linear optical material and a second clad member, the core diameter can be controlled precisely and the clad diameter can be made larger easily. Also, as electrodes for applying voltage are arranged adjacent to both side areas along the groove section, the crystal orientation and refractive index can easily be controlled. In addition, the groove section is formed so as to leave both side faces of the first clad member, so that degradation of the organic non-linear optical material filled in the core as well as degradation of the coupling efficiency can be prevented.

Wavelength conversion element

A fiber type optical wavelength converter comprising a core, and a clad. The core is made of nonlinear optical crystal that converts the primary light or straight polarization of a frequency of .omega., which enters and propagates in the direction of the center axis of the core, into a second harmonics having a vibrating surface normal to a vibrating surface of the primary light and having a frequency of 2.omega.. The nonlinear optical crystal also satisfies n.sup..omega. .gtoreq.n.sup.2.omega. where n.sup..omega. is a refractive index to the primary light and n.sup.2.omega. is a refractive index to the second harmonics.

A fibre-type light conversion device for converting the wavelength of an incident light comprises a core and a cladding layer provided around the core. An end surface of the device from which the light beam radiates is made conical, so that the second harmonic wave is collimated without using any additional optical element such as a conical prism. The end surface of the device is formed by a process in which the end surface of the device is polished with a central axis of the device being held at a predetermined angle with respect to a polishing surface while the device is rotated about the central axis.

Fibre-type wavelength converison device

A fiber-type light conversion device comprises: a fiber-type light conversion element having a core made of non-linear optical crystal for changing the wavelength of an incident light to half by the phase matching of Cerenkov radiation; and a collimating optical system for transforming an emergent light beam emitted from the light conversion element into a parallel light beam, wherein the collimating optical system has lenses having a large spherical aberration .DELTA.z. Furthermore, the quantity of spherical aberration .DELTA.z is determined so as to satisfy the following equation of:

Fiber-type light conversion device

A fiber type wavelength converter formed of a core and a clad surrounding the core, the core consisting of a first core formed of a nonlinear crystalline material, for which, when the refractive index to the primary light incident on and guided by the core is represented by .eta.G.sup..omega. and the refractive index to a converted second harmonic is represented by .eta.G.sup.2.omega., the relationship .eta.G.sup.2.omega. &gt;.eta.G.sup..omega. holds, and a second core formed of optical glass covering the first core. Specifically, the optical glass for the second core is such optical glass, for which, when the refractive index thereof to the primary light incident thereon is represented by .eta.GL.sup..omega., the relationship ##EQU1## holds.

A fiber type light wave-length converting apparatus having a fiber type light wave-length converting element and an axicon lens. The fiber type light wave-length converting element is arranged to a position relative to the axicon lens satisyfing a predetermined condition, whereby an SH wave of a parallel light having a circular intensity distribution is obtained.

Fiber type light wave-length converting apparatus

A fiber wavelength modulator device which emits a secondary harmonic component by Cerenkov radiation, including a core being a single crystal of a non-linear optical material and a cladding being composed of glass, wherein the relative difference between the core and the cladding has a refraction index with respect to an incident beam, of at lesat 0.015.

Optical fiber nonlinear wavelength modulator device

A fibre-type light wavelength conversion device for converting the wavelength of an incident light beam and issuing the incident light beam as a light beam having a predetermined wavelength, having a core and a cladding layer around the core. The device is characterized by the provision of a transparent cylindrical layer provided around the cladding layer, having a refractive index substantially equal to the refractive index of the cladding layer and having a predetermined wall thickness. According to a feature of the invention the wall thickness is determined so that the condition d&gt;l tan .theta. is satisfied, where d represents a diameter of said cylindrical layer, l represents an operating length of the device, and .theta. represents Cerenkov angle.

Fibre-type light wavelength coversion device

A fibre-type light conversion device comprises a fibre-type light conversion element for converting the wavelength of an incident light and an optical system which introduces a light beam from a light source to the light conversion device as the incident light. The optical system is provided with a phase-shifting device which rotates the plane of polarization of the incident light. With this provision it is possible to set the efficiency of light conversion at a maximum level without necessity of rotating the light conversion element.

Growing community of inventors

Saitama, Japan

Sota Okamoto