Transmittance investigation on capacitive mesh on thick dielectric substrates as output windows for optically pumped terahertz lasers

• 来源期刊: 中国物理B（英文版）
• 关键词: physical optics capacitive mesh structure output coupler optically pumped Terahertz laser
• 年，卷（期）: 2010,（11）
• 页码范围: 389-394
• 页数: 6页
• 语种: 英文

摘要

This paper reports that an output window for optically pumped terahertz(THz)laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate(approximating to 5 mm thick).Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation,a nickel film approximating to 1.5μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s.A transmittance spectrum of the output window in a certain frequency range(say,from zero to 1 THz)has been obtained by using THz time domain spectroscopy.Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model(TLM)containing attenuation component from dielectric substrate.The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz.Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers.