LIGHT EMITTING DEVICE, METHOD OF EMITTING SIGNAL LIGHT, METHOD OF SENDING SIGNAL LIGHT, OPTICAL COMMUNICATION SYSTEM AND METHOD OF DETERMINING ISOLATION VALUE

摘要

PROBLEM TO BE SOLVED: To offer a light emitting device, a method of emitting signal lights, a method of sending signal lights, an optical communication system and a method of determining an isolation value, which can attain a specified characteristic of bit error. SOLUTION: A light emitting device 1A is provided with a light generating part, an output and a light isolator 42. The light emitting part includes a semiconductor optical amplifier(SOA) 16 and a grating fiber(GF) 14. The SOA 16 comprises a light emitting plane and a light reflecting plane, and the GF 14 comprises a diffraction grating 14c arranged in a core part and an end part which is connected with the light emitting plane optically. The output is arranged so as to offer the light generated in the light generating part. The light isolator 42 is placed between the light generating part and the output. As for the light emitting device 1A, isolation of the light isolator 42 is specified to be -52.4-8.7×log(BER)or less at a dB unit regarding a bit error rate BER which is supposed to be attained at a transmission velocity 2.5 Gbps in a zone of 1.55 μm.