Fujitsu Corporation

Hideki Isono

Kiyoshi Terai

Tatsuro Kunikane

Kaoru Moriya

Michihiro Takamatsu

Junko Watanabe

Hiroki Okushima

Takashi Yokota

Kazushi Asanuma

Eiji Kikuchi

Tadao Shingyoji

A Mach-Zehnder optical modulator with an output light monitoring function whereby emitted light from the modulator is monitored for controlling a DC bias voltage applied between a first and a second electrode provided on a first and a second branch optical waveguide. The end face of the waveguide substrate on the output side is obliquely formed and an optical waveguide is provided on the waveguide substrate for taking out reflected light from the output end face as monitor light. A photodetector for detecting the monitor light is attached to the side face of the waveguide substrate. By such arrangement, the length of the waveguide substrate can be made shorter than that in the prior art. As an alternative, such an arrangement may be made that a double refraction crystal for separating monitor light is attached to the end face on the output side of the waveguide substrate and a prism for correcting optical path is attached to the double refraction crystal.

Mach-Zehnder optical modulator with monitoring function of output light

An optical waveguide device which can be connected with an optical fiber through a simple positioning adjustment. The optical waveguide device comprises a substrate, a first cladding with a uniform thickness formed on the substrate, a core formed on the first cladding, a recognizable thin layer formed on the first cladding on both sides of the core, and a second cladding formed on the first cladding so as to cover the core. The thin layer is parallel to the top surface of the substrate and defines a reference plane which is substantially in the same plane as the bottom surface of the core. Connection of the optical waveguide device with the optical fiber is achieved by bringing the reference plane into contact with a plane which is in a predetermined relative position to the optical fiber and only making a planar positioning adjustment with the planes held in contact.

Optical waveguide device and method for connecting optical waveguide and

Optical fiber switching with spherical lens and method of making same

A semiconductor laser module comprising a serial arrangement of a laser assembly for emitting a substantially collimated beam of light, an optical isolator assembly having an optical isolator housed in a tubular package for transmitting the collimated beam of light with less loss in a forward direction than in a reverse direction, and an optical fiber assembly having a lens for converging and directing the beam from the optical isolator assembly into an optical fiber. There is also disclosed a method of optimizing the forward loss and isolation characteristics of the optical isolator assembly through adjustment of its angular position about its optical axis which is set at an angle to that of the laser assembly. For such adjustment, not only the isolator assembly is made rotatable relative to the laser assembly, but also the optical isolator itself is made rotatable within limits relative to the tubular package of the isolator assembly.

Laser module with a built-in optical isolator, and method of adjusting

An optical branching filter branches or mixes lights of n-kind of wavelengths. An input/output port for the light mixed n-kind of wavelengths is provided to one of two surfaces of the transparent block and second input/output parts for forming optical filters allowing only the lights having the predetermined wavelengths to pass therethrough, respectively among the lights in n-kind of wavelengths, but reflecting the lights having other wavelengths, respectively is provided to any one of two surfaces. A first input/output port and n second input/output ports, respectively is formed by an optical waveguide and a lens which optically connects the optical waveguide and first input/output part or a second input/output part. Positions of each second input/output port are selected so that the length of optical paths formed between the lenses of the first input/output port in the second input/output port are in the reverse proportion to the lengths of wavelengths corresponding to the second input/output portions.

Optical branching filter

Growing community of inventors

Yokohama, Japan

Hideki Isono