Sumitomo Osaka Cement Co., Ltd.

Toshio Sakane

Kaoru Higuma

Norikazu Miyazaki

Shingo Mori

Susumu Murata

Tsutomu Saitou

Yoshihiro Hashimoto

Takahisa Fujita

Light having components of frequencies f, fand foutputted from an optical modulator () is monitored, a second light detection means () measures the power Pof all the components, and a first light detection means () measures the power Pwith frequency fcomponent cut out by a filter means (). Based on these light receiving powers (P) and (P), phase differences imparted by the respective DC electrodes of Mach-Zehnder optical waveguides (MZ-A, MZ-B, MZ-C) of the optical modulator () are controlled. The control is performed to minimize the light receiving power (P) and to maximize the light receiving power (P).

Optical modulation device

An optical modulator is provided which includes: an optical splitting part that splits an input light wave into two light waves; two optical waveguides that propagate the two light waves into which the input light wave is split, respectively; a first SSB modulating part that is provided in one of the two optical waveguides and modulates a light wave, which propagates into the first SSB modulating part, with a carrier frequency so that the light wave is converted into a different light wave having a single side band; a second SSB modulating part that is provided in the other of the two optical waveguides and modulates a light wave, which propagates into the second SSB modulating part, with a data signal in order to generate a signal light wave having a different single side band; and an optical combining part that combines the light wave modulated by the first SSB modulating part with the signal light wave generated by the second SSB modulating part.

Optical modulator

An optical modulator which magnifies a modulation index and reduces affection of SBS by suppressing a light source carrier component in an equivalent light source spectral width and performs more long-distance transmission by suppressing one of sideband spectrums generated by a modulation signal to reduce affection of fiber dispersion, having a light branch means that branches input light having a carrier component into two light waves; a SSB modulation means that modulates one branched wave and generates a wave having the carrier component and one sideband spectrum; an intensity adjustment means that adjusts intensity of the carrier component of the other wave; a phase adjustment means that adjusts the phase of the carrier component with respect to at least one of the two waves; and a multiplexing means that multiplexes the two waves passing through the modulation means, and the intensity and phase adjustment means, and emits output light.

The present invention provides an optical modulation element module capable of stably operating for long periods without limiting the operating conditions. An optical modulation element module comprising an optical modulation element, a casewith said optical modulation element being integrated thereto, input output fibersbeing connected to said optical modulation element and also guided to an exterior of said case, a terminal for introducing a modulating signal and a bias adjustment voltage that are to be applied to said optical modulation element, said case being hermetically sealed, is characterized in that said caseis made of a material having almost the same coefficient of linear expansion as the optical modulation element, said optical modulation element is affixed to said case by using a thermoplastic and high-elastic adhesive material, a linear expansion difference between each material of said case and said fiber is less than 16&#xd7;10/&#xb0; C., and a distance between a fixed point of said fiber with said case, and a fixed point of said fiber with said optical modulation element is more than 3 mm.

Optical modulation element module

A method and device for stabilizing operation point and optical output of an external optical modulator. A low-frequency signal below a lower limit of signal frequency band of an input signal inputted to optical modulator is superimposed onto direct current bias. A low-frequency component included in detector output is extracted. On the basis of the low-frequency signal, output of the low-frequency component is normalized, and output-light of light source is controlled in accordance with normalized low-frequency component. Means of controlling optical output of light source, in control of output-light of light source, detects the output-light, compares the value of detected output-light to a standard value of primary optical output, and adjusts the output-light. The standard value is modified according to a ratio of primary value of normalized low-frequency component to a subsequent value, and means controlling optical output of light source is operated on the basis of modified standard value.

Method and device for stabilizing operation point and optical output of external optical modulator

'This invention offer optical modulator module with fulfilling the effective and the stable optical modulation, which stabilizes the emission of semiconductor and control the shift of optic axis between the optical component by the temperature change and so on, when using the semiconductor laser. Peculiarly, the optical modulator module includes, in same package, the semiconductor laser () as light source, the optical modulation device () that has optical waveguide on the surface of the chip made by the element of the electro-optical effect, and the polarization rotating element () between said semiconductor laser and said optical modulation device, for bringing plane of polarization of light from said semiconductor laser () to optimum plane of polarization in waveguide of the said optical modulation device in line and blocking the returning light from said optical modulation device to said semiconductor laser.'

Growing community of inventors

Tokyo, Japan

Toshio Sakane