光子学报, 2015, 44 (8): 0819001, 网络出版: 2015-09-08
Al、S和Te掺杂GaSe晶体的光学及倍频特性
Optical and Second Harmonic Properties in Al,S and Te Doped GaSe Crystals
非线性光学 晶体 掺杂 透过率 倍频 相位匹配 Nonlinear optics Crystal Doped GaSe GaSe Transparency Second harmonic Phase matching
摘要
对不同浓度Al、S和Te掺杂GaSe晶体的透过率和倍频特性进行了研究.结果表明,适宜浓度的掺杂晶体在透明波段内吸收系数约为α≤0.1~0.2 cm-1,适于非线性应用.GaSe:S晶体透过率曲线向短波方向移动,且更适于高浓度掺杂,而Al和Te掺杂晶体透明范围的波段截止波长向长波方向移动,且移动幅度小于S掺杂晶体,当掺杂浓度达到GaSe:Al (0.5 mass%)和GaSe:Te (5 mass%)时,晶体光学质量明显下降.通过fs Ti:Sapphire激光和CO2激光泵浦下I类倍频实验发现,S掺杂晶体相位匹配曲线向短波方向移动,倍频输出功率比纯GaSe晶体有明显提高,最佳掺杂浓度为2 mass%.Al和Te掺杂晶体相位匹配角与纯GaSe晶体相比没有明显变化,实验结果与理论曲线符合较好.利用非线性方法研究发现当掺杂浓度不超过5 mass%时,GaSe:Te晶体与纯GaSe同样属于六角形结构.三种掺杂方式最佳掺杂浓度分别为GaSe:Al (0.1 mass%),GaSe:S (2 mass%)和GaSe:Te(0.5 mass%),在CO2激光泵浦下,三者频率转换效率之比约为1:0.6:0.5.在所使用的晶体样本中,GaSe:S (2 mass%)晶体性能最佳,其频率转换效率可达纯GaSe晶体的3倍左右.
Abstract
The transparency and second harmonic properties of Al,S and Te doped GaSe crystals were studied.Low absorption coefficients of α≤0.1~0.2 cm-1 are found in crystals with suitable doping level in transparent range which can be used in nonlinear devices.High doping level is allowed in GaSe:S crystals whose transparency spectra shift towards to short-wavelength range.The short wavelength transparency cut-off of both Al and Te doped crystals shifts more slowly than S doped crystals towards to opposite direction.The optical quality of the crystals has declined markedly when the doping concentration up to GaSe:Al (0.5 mass%) and GaSe:Te (5 mass%).The phase matching curves shift towards to short-wavelength and output power is significantly higher in S doped GaSe crystals than that in pure GaSe crystals with fs Ti:Sapphire laser and CO2 laser pumping.The optimal doping concentration is ascertained as 2 mass%.No obvious differences of type I second harmonic phase matching angle between Al,Te doped and pure crystals are found.The experimental results are in good agreement with theoretical curve.GaSe:Te crystals are found to possess the hexagonal structure like ε-GaSe when the doping concentration is no more than 5 mass% with nonlinear method.The SHG efficiency ratio of the optimal doped crystals GaSe:Al (0.1 mass%),GaSe:S (2 mass%) and GaSe:Te (0.5 mass%) is about 1:0.6:0.5 under CO2 laser pumping.GaSe:S (2 mass%) crystal shows the best performance whose efficiency is about 3 times higher than that in pure GaSe among all used samples.
冯志书, 李晓明, 于丹, 康智慧, 高锦岳. Al、S和Te掺杂GaSe晶体的光学及倍频特性[J]. 光子学报, 2015, 44(8): 0819001. FENG Zhi-shu, LI Xiao-ming, YU Dan, KANG Zhi-hui, GAO Jin-yue. Optical and Second Harmonic Properties in Al,S and Te Doped GaSe Crystals[J]. ACTA PHOTONICA SINICA, 2015, 44(8): 0819001.