Diving angle optimization of BRF in a single-frequency continuous-wave wideband tunable titanium:sapphire laser
Authors：Jiao Wei , XueChen Cao , Pixian Jin ,Jing Su Huadong Lu* ,Kunchi Peng
In this study, the optimal condition of a multi-plate birefringent filter (BRF) used in a single-frequency continuous-wave (CW) tunable laser is theoretically and experimentally investigated. The dependence of the optimal condition on the diving angle of the BRF optical axis is first deduced. Based on the proposed optimal condition, the diving angle of the BRF optical axis is optimized to 29.1 ° . Subsequently, a novel off-axis multi-plate BRF with a thickness ratio of 1:2:5:9 and the thinnest plate of 0.5 mm is designed and utilized in a tunable titanium:sapphire (Ti:S) laser. As a result, the operating wavelength of the Ti:S laser is successfully tuned from 691.48 to 995.55 nm by rotating the BRF 18 ° . The obtained tuning slope efficiency and maximum tuning range are 16.9 nm/ ° and 304.07 nm, respectively. The experimental results agree well with the theoretical analysis results, which provide a feasible approach for designing BRFs to satisfy the requirements of other single-frequency CW wideband tunable lasers.
Realization of compact Watt-level single-frequency continuous-wave self-tuning titanium: sapphire laser
Authors：Jiao Wei ,Xuechen Cao , Pixian Jin , Zhu Shi , Jing Su , HuaDong Lu*
Here, we present a compact Watt-level single-frequency continuous-wave (CW) self-tuning titanium:sapphire (Ti:S) laser, which is implemented using a three-plate Ti:S crystal as both a gain medium and frequency-tuning element. The thickness ratio of the three-plate Ti:S crystal is 1:2:4, of which the thinnest plate measured 1 mm. The optical axes lie on their own surfaces and parallel to each other. Based on the presented self-tuning crystal, a ring resonator is designed and built. The maximum wavelength tuning range of the single-frequency self-tuning Ti:S laser is 108.84 nm, as demonstrated experimentally by rotating the three-plate Ti:S crystal, indicating good agreement with theoretical prediction. To the best of our knowledge, this is the first study to report a single-frequency CW self-tuning Ti:S laser, which can provide a feasible approach for achieving a compact all-solid-state single-frequency CW-tunable Ti:S laser.
Influence of the pump scheme on the output power and the intensity noise of a single-frequency continuous-wave laser
Authors：Yongrui Guo , Weina Peng , Jing Su , Huadong Lu* , Kunchi Peng
The influence of the pump scheme on the intensity noise of the single-frequency continuous-wave (CW) laser is investigated in this paper, which is implemented in a single- frequency CW Nd:YVO 4 1064 nm laser by comparing the traditional 808 nm pumping scheme (TPS) to the direct 888 nm pumping scheme (DPS). Under the conditions that the lasers with TPS and DPS have the same cavity structure and the cavity mirrors, as well as the same operation state including the thermal lens of the laser crystals and the mode-matching between the pump laser mode and the laser cavity mode at the laser crystals, the output power of the laser with DPS is up-to 32.0 W, which is far higher than that of 21.1 W for the laser with TPS. However, the intensity noise of the DPS laser including resonant relaxation oscillation (RRO) frequency of 809 kHz, RRO peak amplitude of 31.6 dB/Hz above the shot noise level (SNL) and the SNL cutoff frequency of 4.2 MHz, respectively, is also higher than that of 606 kHz, 20.4 dB/Hz and 2.4 MHz for the TPS laser. After further analyses, we find that the laser crystal with high doping concentration and long optical length is employed for DPS laser in order to improve the pump laser absorption efficiency, which can simultaneously increase the dipole coupling between the active atoms and the laser cavity, and then results in a high RRO frequency with a large amplitude peak as well as a high SNL cutoff frequency of the laser.