generation of high efficient quasi-single-cycle 3 and 6 thz pulses using multilayer structures oh1/sio2 and dstms/sio2

We propose that high efficient terahertz (thz) multilayer structures are composed of dst m s/sio2 and oh1/sio2 at 3 and 6 t hz frequencies. we show that the efficiencies of these structures are higher than dast /sio2 structure in both of 3 and 6 t hz frequencies. oh1/sio2 structure at 6 thz has an efficiency as large as 10^−1; at 3 t hz frequency, dst ms/sio2 structure has an efficiency as large as 10^−2. meanwhile bulk oh1 has an efficiency as large as 10^−3 at 3 t hz due to perfect phase matching whose efficiency is lower than dst m s/sio2 structure. we also show that other structures, namely dstm s/znt e at 3 t hz and dast /gap at 8 t hz, have low efficiency, so they are not suitable as t hz sources.