1. Mainly used in amplifier, optical receiver and optical emitter.

2. Optical receiver for receiving a signal m-valued star-shaped quadrature amplitude modulation with differential phase coding and application of same

3. An electronic dispersion compensation (EDC) arrangement for a multi-channel optical receiver utilizes a time division technique to 'share' a common adaptive algorithm block between a plurality of N separate channels.

4. The optical receiver includes an image sensor in which an image of the light source is formed; and an image processor detecting a position and brightness of the image formed in the image sensor.

5. The present invention relates to a passive wavelength division multiplexing device for automatic wavelength locking and a system thereof including an optical multiplexer, an optical filter, an integrated optical receiver monitor, and a tunable optical transmitter.

6. The three essential elements of optical communication were invented by Jun-ichi Nishizawa: the semiconductor laser (1957) being the light source, the graded-index optical fiber (1964) as the transmission line, and the PIN photodiode (1950) as the optical receiver.