Tan Yan-Nan, Jin Long, Cheng Linghao, Quan Zhan, Li Mengping, Guan Bai-Ou
Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
Opt Express. 2012 Mar 26;20(7):6961-7. doi: 10.1364/OE.20.006961.
A simple technique has been proposed and demonstrated to generate radio-frequency (RF) signal based on a fiber grating laser with multi-octave tunablity. The laser is fabricated by inscribing a wavelength-matched Bragg grating pair in a short section of low-birefringence Er/Yb co-doped fiber. A RF signal can be obtained by beating the two-polarization mode output with its frequency determined by the birefringence within the cavity. By slicing the laser cavity into two sections and then aligning them with a rotated angle, the output beat frequency can be continuously tuned in a multi-octave frequency range as shown in the experiment from 2.05 GHz down to 289 MHz, as a result of the induced change in optical length for each polarization mode. The present technique has the advantages including simple scheme and large tuning range, and the ability of tuning could be further improved by use of active fibers with higher birefringence.
一种基于具有多倍频程可调谐性的光纤光栅激光器产生射频（RF）信号的简单技术已被提出并得到验证。该激光器是通过在短段低双折射铒镱共掺杂光纤中写入波长匹配的布拉格光栅对来制造的。通过将两个偏振模式输出进行拍频，可以获得一个射频信号，其频率由腔内的双折射决定。通过将激光腔切成两段，然后以一定旋转角度对齐，由于每个偏振模式的光学长度发生了诱导变化，输出拍频可以在多倍频程频率范围内连续调谐，如实验所示，从2.05 GHz到289 MHz。本技术具有方案简单、调谐范围大等优点，并且通过使用具有更高双折射的有源光纤，调谐能力可以进一步提高。
