Study on the SFG digital imaging by using nanometer polarization control

在本研究中，由于涉及到域反转和微加工技术，因此获得了以下结果，这些技术对所提出的装置的成型至关重要。1)新的畴反转控制方法的提出和证明：提出了一种新的圆形全覆盖电极（FCE）方法，在周期小于2 μm的LiNbO_3 （LN）晶体中制备周期畴反转。首先，提出了圆形电极与晶体点接触的方法，并对圆形电极产生小极化反转的有效性进行了理论分析。其次，在2束激光干涉曝光法制作的抗蚀片上制作了周期为2 μm的圆形电极，并进行了脉冲电压应用域反转实验，对该方法进行了验证。结果表明，在500 μm厚的LN晶体中形成了2μm的周期畴反转。此外，该方法虽然只是一部分，但在0.15 μm范围内实现了反演，证明了该方法的有效性。2)晶体的比电阻与极化反转特性的关系：利用控制比电阻ρ的LN晶体制备小尺寸畴反转，考察了晶体的极化反转特性。对于ρ值比普通LN晶体低几个数量级的black-LN （B-LN）晶体，畴反转阈值电压（V_<th>）为~ 100V，且与ρ^<1/2>成正比。此外，当施加100V到B-LN上时，可以得到均匀的点图案。结果表明，与普通LN晶体相比，利用可控比阻晶体施加较低的阈值电压可以制备小畴反转结构，其阈值电压为1/100或更少。3)利用切片锯制作脊型光波导：利用切片锯制作宽度为5mm、长度为50mm的矩形光波导。叶片转速为30000 rpm，送出速度为0.3 mm/sec。利用氦氖激光器测量了光波导的插入损耗和传播损耗。测得的损耗值分别为1 dB/cm和7 dB。光波导的现有特性是不够的。然而，优化的加工条件可以显示出更好的光波导制造的可能性。少

In this research, the following results were achieved since it was concerned with the domain inversion and microfabrication technologies those became important in malting the proposed device.1)The proposal and the proof of the new domain inversion control method : A new circular form full cover electrode (FCE) method was proposed to fabricate periodic domain inversion in the LiNbO_3 (LN) crystal with a period of 2 μm or less. First of all, it was suggested that the circular electrode provided point contact with the crystal and theoretical analysis was perfornned for the effectiveness of circular electrode to produce small polarization inversion Next, circular electrode of 2 μm period was produced on the resist patterned by 2-beam laser interference exposure method and the pulse voltage application domain inversion experiment was conducted in order to prove the method. As a result, 2μm periodic domain inversion in a 500 μm thick LN crystal was fabricated. Moreover, though it was a part, … More 0.15 μm domain inversion was achieved using this new method and the effectiveness of the proposed circular for FCE method was proved.2)The relation between specific resistance and polarization inversion characteristic of the crystal : The polarization inversion characteristic was examined by the fabrication of small size domain inversion using the LN crystal with controlled specific resistance, ρ. For black-LN (B-LN) crystal, with ρ value fair orders of magnitude lower than of normal LN crystal, domain inversion threshold voltage (V_<th>) was 〜100V and was proportional to ρ^<1/2>. Moreover, uniform dot patterns were fabricated when 100V was applied to B-LN. It was clarified that small domain inversion structure can be fabricated by applying lower threshold voltage which is 1/100 or less times compared to the normal LN crystal using controlled specific resistance crystals.3)Fabrication of the ridge type optical waveguide using the dicing saw : A 5mm width and 50 mm length rectangular optical waveguide was fabricated using a dicing saw. The rotational speed and the sending speed of the blade were 30,000 rpm and 0.3 mm/sec, respectively. The insertion loss and the propagation loss of the optical waveguide were measured using a He-Ne laser. The measured loss values were 1 dB/cm and 7 dB, respectively. The present characteristics of the optical waveguide are not enough. However, optimized processing conditions could show the possibility of better optical waveguide fabrication. Less