| 摘要 |
PURPOSE:To make it possible to surpress noise irrespective of the output level being high or low, by controlling reflectivity of the rear surface and of the front surface of a resonator. CONSTITUTION:On the rear surface 130 of an element, the following five layers 140 are arranged; lambda/4 thick Al2O3, two pairs of lambda/4 thick amorphous Si and lambda/2 thick Al2O3. On the front surface 131 of the element, the following three layers 141 are laminated in order; lambda/4 thick Al2O3, 160Angstrom thick amorphous Si and lambda/2 thick Al2O3. Thus the reflectivity of the rear surface of the element and that of the front surface can be controlled as Rr=90% and Rf=40%, respectively. Thereby, photonoise can not be observed up to the back light quantity of about 0.5-1.5% in both cases of 30mW and 3mW, and consequently noise can be surpressed whether the output is high or low. |
