Yun ZHANG (張 贇)

Offer Organization: 日本学術振興会, System Name: 科学研究費助成事業, Category: 基盤研究(C), Fund Type: -, Overall Grant Amount: - (direct: 3200000, indirect: 960000)
2つの縦モードで同時に発振する2モード発振マイクロチップレーザの出力光（2つのモード光はともに鉛直方向の直線偏光）を直交偏光状態に変換するため，出力光を長さ17 mmのLiNbO3複屈折性結晶に導入して，偏光子と光スペクトラムアナライザを用いてその透過光の性質を入念に調べた．その結果，一方のモード光を消光させると他方のモード光の透過率は常にほぼ最大になり，2つのモード光がほぼ完全な直交偏光状態に変換されることを確認した．その一方で，それらの偏光状態は結晶の温度変化の影響を強く受け，4.0 rad/℃のレートでドリフトすることが明らかになった．そこで結晶全体を覆うことができるアクリル樹脂製のエアシールドを自作し，その内部にペルチエ素子と熱交換用ヒートシンクを配置し，シールド内部に恒温の空気を循環させることにより，結晶の温度変化が±0.01℃以下になるように負帰還制御を行った．その結果，シールド効率（室温の変化に対する結晶の温度変化の割合）として1/25の性能が得られ，透過光の偏光状態を長時間安定に維持することができるようになった．
結晶の温度を安定化した状態で透過光の偏光状態の波長依存性を測定し，波長の変化に対して偏光状態がほぼ直線的に変化することを確かめ，101 GHｚの周波数差に対するδ値の差がほぼπ/2になることを確認した．さらに，結晶の印加電圧を変化させて出力光の偏光状態を追跡する方法で半波長電圧を測定したところ，2つのモード光の平均として1.68±0.02 kVの値を得た．

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (A), Fund Type: -, Overall Grant Amount: - (direct: 35700000, indirect: 10710000)
Prism-coupled KBBF devices were developed by the tight optical contact of the boundary between CaF2 and KBBF with diffusion bonding. The light sources at 7 eV and 8 eV with these devices were supplied respectively to ultra high-resolution photoelectron spectroscopy of superconductive materials and to angle-resolved photoelectron spectroscopy measuring electronic states at 2-dimensional Brillouin zone. High-efficiency, large scale transmission gratings were developed and the wavefront distortion of the diffracted beam due to the bending of the grating were analyzed. A femtosecnd multi-color laser was developed by using these gratings for harmonic generation, resulting in the output powers of 0.5 TW at the fundamental (800nm) and 0.1 TW at the second harmonic respectively at a repetition rate of 1 kHz.. By applying dual broad band frequency doubling to this system, the output energy of 90μJ (45 fs) was obtained at the forth harmonic (220nm) .

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 4100000, indirect: 1230000)
We designed photosensors based on the bacteriorhodopsin (bR) pigment found in the cell membrane of Halobacteria and showed that motion detection is possible using only one sensing element. The photocell consists of a bR dip-coated thin film and electrolyte sandwiched between glass plates with ITO electrodes. We fabricated a simple direction sensor by patterning the bR films on electrodes. When light scans the sensing area, the edges of each pattern produce a positive or negative current depending on the light's speed and direction. These direction sensors also respond strongly to rapidly moving objects, though not at all to slow ones. Eventually we replaced ITO/glass with conductive polymer/plastic based on PEDET:PSS. The flexible sensor showed almost the same response as ITO/glass sensor, but couldn't sufficiently respond. The hybrid sensor with protein and conductive polymer will lead to large sensing area system and could be utilized for robot vision applications.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 4000000, indirect: 1200000)
Optical parametric oscillators are useful devices in various fields as the tunable coherent light sources. It is, however, difficult to obtain the stable tunable oscillation which has a low threshold in continuous-wave (cw) optical parametric oscillators. In this study, an efficient cw optical parametric oscillator with a periodically poled KTP (PPKTP) has been developed by using a triple-cavity differential-control configuration. Accordingly, the continuous tuning of the cw OPO has been achieved with a low threshold.