| 摘要 |
PURPOSE:To obtain a light source which can be utilized for the reflection measurement of an optical frequency area by providing an optical amplifier and optical frequency shifter on internal optical path of an optical resonator. CONSTITUTION:A light source 11 having a narrow line width outputs continuous light and an optical modulator 12 modulates the continuous light into rectangular pulsed light having a pulse width (a) and cycle period (b) and makes the pulsed light to be incident to an optical resonator from a half-mirror 13. A frequency shifter 17 performs constant frequency shifting on the incident pulsed light whenever the light makes one turn in the optical resonator. Losses, such as the reflection losses of half mirrors 13 and 14, insertion loss of the shifter 17, etc., are compensated by means of an optical amplifier 16 and the pulsed light makes numerous turns in the optical resonator while the light receives the frequency shifting. As a result, an optical pulse string in which the light frequency is shifted by a fixed amount is outputted from the half mirror. In addition, when the spatial length of the incident rectangular pulsed light is made equal to the length of the optical resonator, optical pulse strings are continuously outputted without any instantaneous interruption and substantially continuous light can be obtained. |
