| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain a laser module suited to long-distance transmission and high-speed transmission inexpensively and with a high output in a state that a load of a laser is low, signal distortion is small and there is no wavelength variation. <P>SOLUTION: A reflection type modulation module includes: a DFB laser for generating basic waveform light having a fixed wavelengthλm, a fixed power and a fixed polarization plane by a fixed injection current; a half mirror for reflecting a part of the basic waveform light and transmitting a part of modulation light; a polarization rotor for 45°-rotating the polarization planes of the basic wavelength light and the modulation light; a reflection type modulation element having the same thin film structure as a Fabry-Perot laser and a front end face of a low reflectance R of 0.01 to 0.3, arranged on a 45°obliquely twisted position so as to have the same polarization plane as that of the basic waveform light, allowing an injection current to flow proportionally to an electric signal and changing an amplification factor to maintain and amplify the same frequencyλm as the basic waveform light passing the rotor, generating modulation light, and emitting the modulation light to the incident side; and an optical fiber on which the modulation light passed through the half mirror after rotating the polarization plane by 45°is made incident. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
