Nippon Telegraph and Telephone Corporation

Koji Nonaka

Hidehiko Takara

Ippei Shake

Takashi Kurokawa

Yoshiaki Yamabayashi

Kentaro Uchiyama

Hiroyuki Tsuda

Osamu Kamatani

It is the object of the present invention to provide a transmission system that transmits a control signal corresponding to the overhead accommodating time division multiplexing information at a frequency that is the same (or nearly the same) as that of the main signal. In order to attain this object, an optical transmitter broadens in a time range the optical waveform of the OTDM signal having a wavelength &lgr; and the control light having a wavelength &lgr; (&ap;&lgr; ), and multiplexes the signal light having an optical peak intensity set low compared to the OTDM signal peak intensity and sending this to an optical transmission fiber. An optical receiver provides a light splitting means that splits into two parts the transmitted OTDM signal and the control light and outputs one part thereof to an optical time division multiplexing means, and at the same time restores the control light included in the other part of the light to the original optical pulse train, and extracts the control information by converting this to an electric signal.

Optical transmission system

An all-optical swtich apparatus having an optical gate which is unitarily composed of a nonlinear etalon and a pair of GRIN lenses, or a nonlinear etalon and a GRIN lens, and having collimating GRIN lenses, each of which guides a signal beam and a control beam to the optical gate. The resonance wavelength of the etalon can be regulated by adjusting the incident positions of signal beam and/or control beam to the optical gate by moving the collimating GRIN lenses. This decreases the required thickness accuracy of the etalon by one or more orders of magnitude than in the conventional technique. Three major types of switches are disclosed: a primary type in which the signal beam is switched by changing the transmittance of the etalon by the control beam; a reflecting type which works as a complementary switch of the primary type; and a transfer type in which the direction of travel of the signal beam is changed by emitting either the transmitted signal beam or the reflected signal beam from the optical gate under the control of the control beam.

All-optical switch apparatus using a nonlinear etalon

Growing community of inventors

Yokosuka, Japan

Koji Nonaka