Shin-etsu Chemical Co., Ltd.

Nippon Hoso' Kyokai

Other

Toshihiko Ryuo

Masayuki Tanno

Toshiaki Watanabe

Yoshiyuki Shiono

Masanori Ikari

Satoru Fukuda

Toshihiro Nomoto

Takao Kuki

Yoshinori Kuwabara

Tatsuo Mori

Hiroki Yoshikawa

Shinji Makikawa

Jun Horikoshi

Shohei Kozakai

Susumu Sakaguchi

Masahiro Ogihara

Kazuyoshi Watanabe

Takeo Kawanake

Takeo Kawanaka

Ken Itoh

Shinji Makigawa

Shin Sugiyama

A polarization-independent optical isolator includes a first birefringent wedge plate having an inclined plane directed to a light incoming side; a second birefringent wedge plate having an inclined plane directed to a light outgoing side, the wedge equal thickness line of the inclined plane of the second birefringent wedge plate being in parallel to the wedge equal thickness line of the inclined plane of the first birefringent wedge plate; and a Faraday rotator element disposed between the first and second birefringent wedge plates. A non-inclined plane of the first birefringent wedge plate is adhesively bonded to a light incoming plane of the Faraday rotator element, and a light outgoing plane of the Faraday rotator element is adhesively bonded to a non-inclined plane of the second birefringent wedge plate. The first and second birefringent wedge plates and the Faraday rotator element thus adhesively bonded to each other are disposed in a cylindrical magnet.

Polarization-independent optical isolator and production method thereof

There is disclosed a piezoelectric single crystal wafer wherein an etching pit density on the front surface of the wafer on which an electrode for transmit-receive of surface acoustic wave or leaky surface acoustic wave is formed is 7.8&times;10 /mm or less, and a piezoelectric single crystal wafer wherein surface roughness Ra on the peripheral surface other than the front surface and the reverse surface of the wafer is 2.3 &mgr;m or less. There can be provided a piezoelectric single crystal wafer wherein a deviation of surface acoustic wave velocity or leaky surface acoustic wave velocity is small, namely the uniformity of the velocity is excellent, and fine contaminations adhered on the surface where electrode is formed and breakage of the wafer can be significantly reduced, and therefore a device such as a filter having excellent property can be produced in high yield.

Piezoelectric single crystal wafer

There is disclosed an optical isolator, wherein one surface of an optical element comprising at least one polarizer and at least one Faraday rotator is bonded and fixed to a substrate in which a height of an optical element bonded portion surface has a level difference from a height of a peripheral portion surface, and the optical isolator, wherein a rectangular parallelepiped optical element comprising at least one polarizer and at least one Faraday rotator, which are bonded in the face of each light-transmitting surface, is bonded and fixed with a bonding agent to the substrate while the Faraday rotator in the optical element is not bonded to the substrate. There is provided a reliable and low cost optical isolator that can bond and integrate an optical isolator element and permanent magnets on a substrate, can realize positional adjustment in assembly with high precision and high bonding strength, and can avoid bonding distortion for an optical element.

Optical isolator

Faraday rotator and magneto-optical element using the same

A piezoelectric single crystal wafer for SAW or LSAW devices has an x-ray rocking curve half width of up to 0.06&deg; on the wafer surface on which electrodes are to be formed for transmitting and receiving SAW or LSAW.

SAW or LSAW device piezoelectric single crystal wafer and method of making

A magnetostatic wave device includes a Gd,Ga,O,substrate off-angled from a &lcub;110&rcub; plane. A magnetic thin film including a crystal of garnet is formed on the Gd,Ga,O,substrate by liquid-phase epitaxy. A transducer operates for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as 20&deg;&lE;&verbar;&thgr;,&plus;&thgr;,&verbar;&lE;35&deg;, where &ldquo;&thgr;,&rdquo; denotes an angle between a longitudinal direction of the transducer and a <001> orientation of the crystal in the magnetic thin film, and &ldquo;&thgr;,&rdquo; denotes an angle between a transverse direction of the transducer and a specified direction. The specified direction is parallel to a line of intersection between a horizontal plane of the magnetic thin film and a given plane which is perpendicular to the horizontal plane of the magnetic thin film and which contains a direction of the bias magnetic field. Also, there is a relation as &verbar;&thgr;,&verbar;&lE;75&deg;, where &ldquo;&thgr;,&rdquo; denotes an angle between the specified direction and the direction of the bias magnetic field.

Magnetostatic wave device with specified angles relating the transducer, magnetic thin film, and bias magnetic field

An improvement is proposed relating to an optical isolator for bonding of the polarizer and analyzer of polarizing glass to the respective holder rings for position adjustment. The improvement comprises: (a) forming a metallized layer of a specific composition over at least two of the side surfaces of each of the polarizer and analyzer on the area of the surface excepting for the linear areas of 50 to 150 .mu.m width from the top and bottom surfaces of the polarizer or analyzer; and (b) bonding the polarizer and analyzer to the respective holder rings by soldering using a solder alloy with intervention of the metallized layer between the polarizer or analyzer and the holder ring. The invention further provides an optical part having, on at least one of the surfaces, a heat-resistant anti-reflection coating film which is a double-layered film consisting of a thin film of the titanium oxide TiO.sub.x (x=1.9 to 2.2) as the underlayer of high refractive index and a thin film of silicon dioxide as the overlayer of low refractive index.

Optical isolator and optical part having heat-resistant anti-reflection

The present multiple-stage optical isolator has low polarization-dependency and low polarization-mode dispersion but does not require a long time for the assembly. It is constructed of a first unit having a first Faraday rotator placed within a magnetic field and at least one birefringent crystal sandwiching the Faraday rotator, these components being arranged in order from the light incident side; and a second unit having a second Faraday rotator placed within a magnetic field and at least one birefringent crystal sandwiching the Faraday rotator, these components being arranged in order from the light incident side, wherein the first and second units are arranged in order along the direction of the light transmission.

Multiple-stage optical isolator

An optical isolator has a high ratio of the quantity of signals S to that of noises N (S/N ratio) and can be miniaturized such a size that it can easily be incorporated into a laser module. The optical isolator 1 according to the present invention is one to be connected to a semiconductor laser 11 having a linear polarization plane and comprises a Faraday's rotator 5 and a magnetic material 4 for establishing a magnetic field around the rotor on the light-incident side of the isolator and an optical material 6 for polarization on the light-outputting side thereof. In particular, the optical isolator 1 of the present invention is one to be connected to a semiconductor laser 11 having a linear polarization plane while aligning a polarization direction guide 3 of the isolator with the semiconductor laser 11, comprises a Faraday's rotator 5 whose light-incident and -outputting sides are desirably inclined with respect to the optical path and an annular magnetic material 4 surrounding the rotator 5, on the light-incident side of the isolator and an optical material 6 for polarization, on the light-outputting side thereof, whose light-incident and -outputting sides are desirably inclined with respect to the optical path, and the optical material for polarization is more desirably made of a metal-containing glass material.

A magnetostatic wave device includes a Gd.sub.3 Ga.sub.5 O.sub.12 substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd.sub.3 Ga.sub.5 O.sub.12 substrate by liquid-phase epitaxy. A transducer is operative for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as 20.degree..ltoreq..vertline..theta..sub.1 +.theta..sub.2 .vertline..ltoreq.35.degree., where '.theta..sub.1 ' denotes an angle between a longitudinal direction of the transducer and a &lt;001&gt; orientation of the crystal in the magnetic thin film, and '.theta..sub.2 ' denotes an angle between a direction of the bias magnetic field and a transverse direction of the transducer which is perpendicular to the longitudinal direction thereof.

Magnetostatic wave device

A reflection-type S/N enhancer includes a Gd.sub.3 Ga.sub.5 O.sub.12 substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd.sub.3 Ga.sub.5 O.sub.12 substrate by liquid-phase epitaxy. The magnetic thin film has a saturation magnetization in a range of 500 G to 1,100 G. A transducer is operative for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as .vertline..theta..sub.1 +.theta..sub.2 .vertline.&lt;45.degree., where '.theta..sub.1 ' denotes an angle between a longitudinal direction of the transducer and a &lt;001&gt; orientation of the crystal in the magnetic thin film, and '.theta..sub.2 ' denotes an angle between a direction of the bias magnetic field and a transverse direction of the transducer in a horizontal plane. The transverse direction of the transducer is perpendicular to the longitudinal direction thereof.

Reflection-type S/N enhancer

Proposed is an improvement in a magnetostatic surface wave device such as an S/N enhancer comprising a thin film chip of a magnetic oxide garnet, e.g., gallium-substituted YIG epitaxially grown on the surface of a substrate, e.g., GGG, to which a magnetic field is applied within the plane of the thin film. The low-pass cut-off frequency of the microwaves can be decreased to 400 MHz or lower and the half-value width of magnetic resonance .DELTA.H can be small enough when the principal plane of the thin film of the magnetic oxide garnet is the (110) plane and the magnetic field applied thereto is in such a direction that the angle between the direction of the magnetic field and the direction of the &lt;100&gt; axis of the thin film within the (110) plane is in the range from .+-.27.degree. to .+-.33.degree..

Thin film chip of magnetic oxide garnet and magnetostatic surface wave

Proposed is an improvement in the method for the preparation of a chip of an oxide garnet film epitaxially having a specific chemical composition as grown on the surface of a GGG substrate wafer having a crystallographic plane orientation of (111), which is useful as a working element in a magnetostatic wave device such as high-frequency filters, signal noise enhancers, isolators and the like with decreased temperature dependence of the properties. The epitaxially grown single crystal film is adjusted to have such dimensions that the thickness h and the smallest dimension L within the plane of the film satisfy the relationship that the ratio h/L is in the range from 0.001 to 0.25.

Growing community of inventors

Gunma, Japan

Toshihiko Ryuo