Jiao Wei, Huadong Lu*, Pixian Jin, Kunchi Peng
A method of evaluating the thermal focal length of nonlinear crystal via transmission spectrum of a swept cavity (TSSC) is presented. By recording the resonant point offset of the TSSC, the thermal focal length can be successfully measured. Furtherly, by distinguishing the absorption of ultraviolet (UV) laser and UV laser induced infrared absorption (ULIIRA), it is clear that the ULIIRA is the important factor which induces the thermal lens effect compared to the absorption of UV laser for MgO-doped periodically poled stoichiometric lithium tantalate (MgO:PPSLT) crystal and it becomes serious with the increase of the generated UV laser. The ULIIRA coefficient measurement and thermal focal length evalution of MgO:PPSLT crystal can supply an useful reference for researchers to generate high quality UV laser and squeezed or entangled state of optical field by using MgO:PPSLT crystal. The presented method can also be used to precisely evaluate the thermal focal length of other nonlinear crystals.
Opt. Express 25(4), 3545-3552(2017) PDF
Yajun Wang, Wenhai Yang, Zhixiu Li, Yaohui Zheng*
Non-classical squeezed states of light at a compatible atomic wavelength have a potential application in quantum information protocols for quantum states delaying or storaging. An optical parametric oscillator (OPO) with periodically poled potassium titanyl phosphate (PPKTP) is the most effective method for generating this squeezed state. However, it is a challege for the nonlinear interaction in PPKTP crystal at the D1 line of rubidium atomic, due to a strong blue-light-induced infrared absorption (BLIIRA). In this paper, we report an indirect measurement method for the BLIIRA through measuring the mode-matching efficiency in an optical parametric oscillator. In contrast to previous works, our method is not limited by the absolute power variation induced from the change of frequency conversion loss and the impedance matching originated from the change of absorption loss. Therefore, the measurement process is performed at the phase-matching condition. The measured results show that BLIIRA coefficient is quadratic dependence of blue light intensity below 1kW per square centimeter in our PPKTP device, which will provide important basis for optimizing squeezed state generation at 795nm.
Sci. Rep. 7, 41405(2017) PDF
Pixian Jin, Huadong Lu*, Yixiao Wei, Jing Su, Kunchi Peng
We present a tunable single-frequency CW Ti:sapphire laser with intensity noise manipulation. The manipulation of the laser intensity noise is realized by varying the frequency of the modulation signal loaded on the electrodes of an intracavity electro-optic etalon. A lithium niobate (LiNbO3) crystal is used to act as the electro-optic etalon, and its electro-optic effect is utilized to modulate the intracavity laser intensity for locking itself to the oscillating wavelength of the laser to implement continuous frequencytuning. When the electro-optic etalon is locked to the oscillating mode of the Ti:sapphire laser with arbitrarily selected modulation frequency, the maximal continuous frequency-tuning range can reach to 20 GHz, and the laser intensity noise is successfully manipulated simultaneously.
Opt. Lett. 42(1), 143-146(2017) PDF