Study of Tunable Ridge-Type Optical Polarization Splitter and Gamma Irradiation Effect
Date Issued
2007
Date
2007
Author(s)
Chang, Chin-Yu
DOI
zh-TW
Abstract
The principle and fabrication of tunable ridge-type optical polarization splitter is studied and the influence of the gamma ray irradiation on the waveguides of the splitter is discussed. The ridge structure on the lithium niobate substrate is fabricated by using a mixture of benzoic acid and adipic acid to have a larger depth-to-width ratio.
The splitter is essentially an asymmetric y-branch waveguide. The lower part is a polarization converter and the upper part is a TE/TM polarization splitter. The polarization converter consists of a nickel indiffusion waveguide and a pair of finger-type electrodes deposited on both side of the waveguide. The two branch of the polarization splitter is fabricated by using nickel indiffusion and annealed proton exchange (APE). Using the process-dependent polarization property of the nickel indiffusion waveguide, the input waveguide supporting both ordinary and extraordinary waves and the straight branch waveguide supporting only ordinary wave are successfully fabricated by choosing proper process parameters. The bent branch waveguide supporting only extraordinary wave is fabricated by APE waveguide due to its property of just supporting extraordinary wave. When an incident laser is passing through the polarization converter, the power ratio of TE and TM polarization can be adjusted by an applied electric field. Then the TE- and TM-polarization powers are split by the following TE/TM polarization splitter.
The extinction ratio of TE and TM polarization are 25dB and 18dB, respectively. When a voltage of 70V is applied to the electrodes, 85% and 50% of the power in TM- and TE-branch waveguide are converted to the power in TE- and TM-branch waveguide, respectively, which are greater than those reported previously.
Moreover, under the irradiation of gamma ray, the ridged APE waveguide exhibits the highest anti-radioactivity. The measured power transmission loss of ridged APE waveguide is 0.06 dB/cm per 10KGy, which is the lowest loss among all the waveguides tested.
Subjects
可調
脊形
光極化分離器
伽瑪輻射
光波導
鋰酸鋰
tunable
ridge-Type
optical polarization splitter
gamma irradiation
optical waveguide
lithium niobate
Type
thesis
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