由级联紫外电光开关控制准分子激光的自发辐射放大
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摘要
考虑高功率准分子激光系统的自发辐射放大(ASE)会导致主脉冲信号对比度下降,引起波形展宽和畸变,本文开展了级联双电光开关的研究来抑制ASE的产生并提高激光脉冲信号的信号对比度。探讨了电光开关的级联工作模式,分析了影响电光开关削波对比度的因素,进而提出采用级联工作方式来大幅度地提高削波对比度。在单电光开关的基础上,设计了级联电光削波的光路布局。其中,前一级电光开关的检偏器作为后一级的起偏器,电路则采用分立式以避免相互之间的串扰。采用级联双电光开关对低占空比预放大器进行了ASE控制实验。实验结果显示,级联双电光开关的削波对比度达到了104量级,而预放大器的放大输出信号对比度提高到106量级,此结果有利于激光脉冲信号在系统中后续放大级的进一步放大。
A cascaded electro-optical(E-O) switch was studied to suppress Amplified Spontaneous Emission(ASE) and promote the signal contrast of the laser pulse,because the ASE could decrease the signal contrast ratio and widen the waveform and distortion in a high power excimer laser severely.The cascaded mode of the E-O switch was explored,the factors that effect on signal contrast ratio of the E-O switch were analyzed,then the work mode using the E-O switch cascaded was proposed to promote the contrast ratio of the switch.On the basis of a single switch,the cascaded E-O switch layout was designed.The analyzer of the first switch was used as the polarizer of the following one,and the driving power supply was installed discretely to avoid the crosstalk.An experiment on ASE suppression for the low duty cycle of a pre-amplifier was performed using a cascaded double E-O switch.The results show that the contrast ratio of the cascaded switch reaches 104 level and the signal contrast ratio of the pre-amplifier output pulse reaches 106 level,which is beneficial to the amplification of laser pulse signals in following amplifier stages of the system.
A cascaded electro-optical(E-O) switch was studied to suppress Amplified Spontaneous Emission(ASE) and promote the signal contrast of the laser pulse,because the ASE could decrease the signal contrast ratio and widen the waveform and distortion in a high power excimer laser severely.The cascaded mode of the E-O switch was explored,the factors that effect on signal contrast ratio of the E-O switch were analyzed,then the work mode using the E-O switch cascaded was proposed to promote the contrast ratio of the switch.On the basis of a single switch,the cascaded E-O switch layout was designed.The analyzer of the first switch was used as the polarizer of the following one,and the driving power supply was installed discretely to avoid the crosstalk.An experiment on ASE suppression for the low duty cycle of a pre-amplifier was performed using a cascaded double E-O switch.The results show that the contrast ratio of the cascaded switch reaches 104 level and the signal contrast ratio of the pre-amplifier output pulse reaches 106 level,which is beneficial to the amplification of laser pulse signals in following amplifier stages of the system.
引文
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[2]OBENSCHAIN S P.The Nike KrF facility.proc ofexcimer lasers for fusion&industrial application[C].Erice-Sicily,Italy,Nov.29-Dec.4,1997.
[3]DENIZK P M S,GOLDHAR Y V.Nanosecondswitching,high-contrast Pockels cell with plasma e-lectrodes[C].CLEO’96,1996,122:435-436.
[4]DENIZ A V,OBENSCHAIN S P.A KrF oscillatorsystem with uniform profiles[J].Optics.Comm,1994,106:113-118.
[5]赵学庆,刘晶儒,易爱平,等.平滑化窄脉冲高功率准分子激光放大技术[J].光学精密工程,2011(2):397-406.ZHAO X Q,LIU J R,YI A P,et al..Amplifica-tion of high power short pulse excimer laser withbeam smoothing[J].Opt.Precision Eng.,2011(2):397-406.(in Chinese)
[6]薛全喜,赵学庆,华恒祺,等.高功率XeCl准分子激光系统前端平滑实验[J].光学精密工程,2011(2):332-339.XUE Q X,ZHAO X Q,HUA H Q,et al..Seedbeam smoothing for high power XeCl excimer lasersystem[J].Opt.Precision Eng.,2011(2):332-339.(in Chinese)
[7]向世清,董景星,莽燕萍,等.电光开关削波产生2～10ns准分子激光输出脉冲[J].中国激光,1995(22):675-680.XIANG SH Q,DONG J X,MANG Y P,et al..Generation of 2-10ns XeCl laser pulses by directwave clipping with an electro-optical q-switching[J].Chinese J.Lasers,1995,22:675-680.(in Chi-nese)
[8]孟绍贤,谷忠民,莽燕萍,等.电光开关削波和激光放大过程中的脉冲变窄[J].中国激光,1998(10):930-934.MENG SH X,GU ZH M,MANG Y P,et al..Chopped waveshape of electro-optic gates and short-en pulses in laser amplification process[J].ChineseJ.Lasers,1998(10):930-934.(in Chinese)
[9]李世忱,倪文俊,杨天新,等.KTP(KTiPO4)晶体电光开关研究[J].光电子.激光,1999(10):95-98.LI SH CH,NI W J,YANG T X,et al..Studieson crystal KPT(KTiPO4)electro-optic switch[J].Journal of Opto-Electronics.Laser,1999(10):95-98.(in Chinese)
[10]卢秀权,陈绍和.KTP电光开关[J].中国激光,1999,26:321-324.LU X Q,CHEN SH H.KTP electro-opticalswitch[J].Chinese J.Lasers,1999,26:95-98.(in Chinese)
[11]任钢,郑建刚,蔡邦维,等.离轴光线对电光晶体退偏的影响[J].强激光与粒子束,2004(16):59-62.REN G,ZHENG J G,CAI B W,et al..Influenceof off-axis-light on depolarization loss of electro-optical crystal[J].High Power Laser and Parti-cle Beams,2004(16):59-62.(in Chinese)
[12]胡云,赵学庆,薛全喜,等.用于紫外激光的BBO电光削波开关[J].激光与光电子学进展,2010(11):111401-1-111401-5.HU Y,ZHAO X Q,XUE Q X,et al..BBO elec-tro-optical switch for UV laser[J].Laser&Op-toelectronics Progress,2010(11):111401-1-111401-5.(in Chinese)