| 摘要 |
PURPOSE:To enable feed-back control at a high speed, not necessarily require a complicated laser device, by detecting the wavelength jump of a laser chip and feeding back it to an element current or temperature. CONSTITUTION:A semiconductor laser chip 1 is fixed on a silicon submount 2, which is fixed on a metal stem 3. Two-split photodiodes 6, 6' for detecting the backward emitting light of the chip 1 are provided. After light from the rear of the laser chip passes a plurality of optical paths, interference moire is formed on the photodiodes. A detector converts a current generated in the photodiode to a voltage by amplifiers 8, 9 having voltage/current converting resistors R1, R1' to obtain detection output VOUT by a differential amplifier 10. The VOUT is compared by a comparator 11 with reference value Vref, a wavelength jump can be detected. Accordingly, a discontinuous variation is detected and fed back to a laser driving current or an element temperature, thereby stabilizing the wavelength. |
