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Study on nonlinear absorption and photorefractive effect in optical fibers using a tunable dye laser

利用可调谐染料激光器研究光纤中的非线性吸收和光折变效应

基本信息

批准号：
05452205
负责人：
MIZUNAMI Toru
金额：
$ 4.22万
依托单位：
Kyushu Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452205/
关键词：
Nonlinear optics Photorefractive effect Silica glass fiber Two-photon absorption Dye laser Fiber grating

项目摘要

The purpose of this research is to make clear the nonlinear absorption (two-photon absorption) and UV- or blue-induced photorefractivity in optical fibers and to fabricate fiber gratings as an application of photorefractivity. In 1993, we performed a preliminary measurement on two-photon absorption (TPA) in an optical fiber using a tunable dye laser, and we also measured the TPA spectrum in the ultraviolet region. In 1994, we carried out a detailed measurement on TPA spectrum in the blue region and a direct measurement on the photorefractive index change, and we fabricated fiber Bragg gratings.The measurement on TPA spectrum in the blue region was preformed in the range of 440-560 nm using a germanosilicate fiber. The measured TPA coefficient showed a maximum value of 1x10^<-4> cm/MW at 480 nm. This indicates that the TPA is due to Ge-Si and Ge^<2+> defects having absorption spectra around 240 nm. In the ultraviolet region of 219-260 nm, the TPA coefficient in pure silica fibers increa … More sed rapidly with the decrease in the wavelength.To investigate the photorefractive index change, we made a measurement system using an interference in a fiber coupler and irradiate the fibers with a KrF excimer laser. We showed that two different mechanisms contribute to the index change, and identified them as absorption by Ge-Si and Ge^<2+> defects.For studies on fiber gratings, we made an apparatus of holographic exposure on fibers with an injection-locked KrF excimer laser as a light source. Using multishot exposure of laser pulses, gratings with excellent reflectivity of 99% was obtained with a short exposure time of 2 minutes. Using single shot exposure, a reflectivity of 90% was obtained. Contribution of Ge^<2+> has been dominant in multishot exposure. We also performed a numerical analysis of solitons, as compression of solitons are expected using fiber gratings.Presently we have been performing the experiment on tuning of Er-doped fiber lasers using the fiber gratings we fabricated. Less

本研究的目的是弄清楚光纤中的非线性吸收(双光子吸收)和紫外光或蓝光诱导的光折变，并制作光纤光栅作为光折变的应用。1993年，我们利用可调谐染料激光器对光纤中的双光子吸收(TPA)进行了初步测量，并测量了紫外区的TPA光谱。1994年，我们对蓝光区域的TPA光谱进行了详细的测量，并直接测量了光折变系数的变化，制作了光纤布拉格光栅，利用锗硅酸盐光纤在440-560 nm范围内对蓝光区域的TPA光谱进行了测量。测得的TPA系数在480 nm处的最大值为1×10~(-4)cm/mW。这表明TPA是由于吸收光谱在240 nm附近的Ge-Si和Ge^&lt；2+&gt；缺陷引起的。在219-260 nm的紫外区，纯石英光纤的双光子吸收系数增加了…为了研究光纤折射率的变化，我们在光纤耦合器中制作了一个干涉测量系统，并用KrF准分子激光器对光纤进行辐照。在光纤光栅的研究中，我们以注入锁定的KrF准分子激光器为光源，制作了光纤全息曝光装置。利用激光脉冲的多次曝光，在短曝光时间为2分钟的情况下，获得了反射率为99%的优良的光栅。使用单次曝光，获得了90%的反射率。在多镜头曝光中，Ge^&lt；2+&gt；的贡献占主导地位。我们还对孤子进行了数值分析，因为孤子有望用光纤光栅进行压缩。目前，我们一直在利用我们制作的光纤光栅对掺Er光纤激光器进行调谐实验。较少