Iodine-stabilized Single Frequency External Cavity Green Diode Laser

Yi-Hsi Chen¹, Wei-Chen Lin¹, Hong-Zhi Chen¹, Kuan-Ting Shen¹, Jow-Tsong Shy², Chin-Chun Tsai^1,3, Hsiang-chen chui^1*

¹Department of Photonics, National Cheng Kung University, Tainan, Taiwan
²Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
³Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Hsiang-chen chui, email:hcchui@mail.ncku.edu.tw

We presented a design of a single-frequency green InGaN external cavity diode laser (ECDL) with 40-mW output power and 5.1-MHz linewidth. Then, the frequency stabilization using a saturated absorption spectroscopy method based on iodine hyperfine transitions can be realized with direct laser diode (LD) output and the ECDL. Furthermore, the uncertainty of the frequency stabilization can be estimated as 8x10^-9 at a 10-s integration time using direct LD and can be pushed to 2.2×10^-11 using the ECDL. This study indicates that ultra-stability frequency reference within the green region can be achieved with the ECDL as opposed to the diode-pumped frequency-doubled solid-state laser. We also analyzed the output efficiency of the ECDL under different polarization directions and emitted light patterns. The laser spectrum under the different applied currents and temperatures were also investigated. we obtained the information of tuning range and linewidth with applied current.

Keywords: Laser diode, saturated absorption spectroscopy, frequnecy references