超高精细度光学腔中低损耗的测量

Measurement of ultra-low losses in optical supercavity

对高精细度光学腔的微弱损耗进行了测量 .利用不同扫描速度下的腔衰减振荡信号 ,得到了腔的衰荡时间 .通过与相同镜面组成的超短微腔的直接精细常数的测量对比 ,说明了这种方法的可靠性 .本实验通过对所得到的光腔衰荡信号的衰荡时间、衰荡强度变化进行计算处理得到光学腔的精细度为F =(2 .13± 0 .0 9)× 10 5;得到腔镜的反射率为R =0 .999985 2± 0 .0 0 0 0 0 0 6 ,即腔的总损耗为 (2 9.5 0± 1.2 4 )ppm .由于该腔的线宽在 10 0kHz以下 ,远低于一般的半导体激光器线宽 ,因此可以利用此腔来测其线宽 .实验中测得DBR半导体激光器的线宽为 1.4 9MHz.

The ultra-low losses of the supermirror is measured by cavity-ringdown technique with a relative short cavity and independently with the directly finesse measurement of a microcavity with the same supermirrors. The measured cavity finesse is F(2.13±0.09)×105 and F(2.03±0.01)×105 respectively, and the total cavity losses are (29.50±1.24)ppm and (30.15±0.15)ppm. We also used the supercavity to measure the linewidth of a DBR diode laser.