テラヘルツパルス光波形整形装置の開発

Pulse shaping for terahertz laser pulses

坪内 雅明; 熊田 高之   

Tsubouchi, Masaaki; Kumada, Takayuki

近年のテラヘルツ(THz)光発生技術の急速な進展により、これまで分子を「観測」するための分光手段として用いられてきたTHz光は、分子を「制御」する方法としてもその可能性を拡げつつある。そこで本研究では、分子制御のために必要なTHzパルス光波形整形技術の開発を目指し、その基盤技術の一つとしてテラヘルツ周波数領域で動作する小型の高効率エタロン素子を開発した。講演では当エタロン素子の概要とその実用例を紹介し、将来的な任意波形整形器製作に向けた基礎実験について紹介する。

We have introduced a novel etalon device for THz laser pulses to generate THz laser pulse trains. The etalon usually consists of a pair of the high reflective mirrors. Therefore, a large amount of input light is reflected by the input mirror, and cannot be transferred to the pulse train efficiently. We have solved this intrinsic problem of the etalon by using an optical switch. Our THz etalon consists of a thin silicon (Si) plate as an input coupler and a glass coated by the indium tin oxide (ITO) as an output coupler. The Si plate is transparent for THz light, and the ITO membrane strongly reflects it. After the THz pulse transmits the Si plate, the Si is irradiated by a UV light pulse to generate the plasma sheet which strongly reflects the THz light. The UV light operates as an optical switch which traps the THz pulse in the etalon cavity. The small portions of THz light are transmitted through ITO in each round trip, and form the pulse train.