Nippon Telegraph and Telephone Corporation

Kenichi Kubodera

Takashi Kurihara

Shiro Matsumoto

Hirohisa Kanbara

Shoichi Sudo

Yoshihisa Sakai

Toshikuni Kaino

Itaru Yokohama

Yuzo Yoshikuni

Tetsuhiko Ikegami

Hiroshi Yasaka

Toshikuni Kainou

A method of stabilizing the frequency of a semiconductor laser comprises stabilizing a time-dependent frequency fluctuation by utilizing an optical energy absorption medium including an isotope acetylene gas molecule. An apparatus for stabilizing the frequency of a semiconductor laser, comprises a semiconductor laser, an optical energy absorption medium, a photodetector and a control circuit as essential elements. The optical energy absorption medium includes an isotope acetylene molecule.

Method and apparatus for stabilizing frequency of semiconductor laser

A nonlinear optical device having an optical medium and an optical element including a polarizer, an optical resonator and a reflector is provided. The optical medium includes an organic nonlinear optical material represented by a formula: ##STR1## wherein each of R.sub.1 and R.sub.2 is an alkyl group having 2 to 6 carbon atoms or a hydroxyalkyl group having 2 to 6 carbon atoms, R.sub.1 and R.sub.2 being same or different groups; or R.sub.1 is an ethyl group and R.sub.2 is an acryloyloxyethyl group (CH.sub.2 .dbd.CH--COO--CH.sub.2 CH.sub.2 --) or a methacryloyloxyethyl group (CH.sub.2 .dbd.C(CH.sub.3)--COO--CH.sub.2 CH.sub.2 --); and each of X.sub.1, X.sub.2, X.sub.3, and X.sub.4 is individually a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group, an alkoxy group, an alkyl ester group, or an alkylamide group, where X.sub.1, X.sub.2, X.sub.3 and X.sub.4 may be the same or different groups.

Organic nonlinear optical material and nonlinear optical device

An organic nonlinear optical device having a nitrostyrene compound represented by a formula: ##STR1## wherein R.sub.1 is an ethyl group R.sub.2 is a group selected from the group consisting of an acryloyloxyethyl group (CH.sub.2 .dbd.CH--COO--CH.sub.2 CH.sub.2 --) and a methacryloyloxyethyl group (CH.sub.2 .dbd.C(CH.sub.3)--COO--CH.sub.2 CH.sub.2 --); and X.sub.1, X.sub.2, X.sub.3, and X.sub.4 are the same or different and each is selected from the group consisting of a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group, an alkoxy group, an alkyl ester group, and an alkylamide group, is provided.

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Isehara, Japan

Kenichi Kubodera