VUV/O3 assisted single crystal quartz bonding with amorphous SiO2 intermedicate layer for manufacturing optical low pass filter

Abstract

We proposed a single crystal quartz direct bonding method utilizing amorphous SiO2 intermediated layers, which can improve heat resistance of the optical low pass filter (OLPF) by novel fabrication method. An amorphous SiO2 was deposited on the opposite sides of both infrared reflection and anti-reflection coated substrates to prepare the highly activated surfaces. The substrates were bonded at 200 °C after the vacuum ultraviolet (VUV) /O3 pre-treatment. The bonded sample with amorphous SiO2 layer shows 5 times higher tensile strength than that without amorphous SiO2 layer while it keeps nearly 100% of light transmittance. These results indicate that amorphous SiO2 layer could prepare activate surface even in low vacuum bonding condition. This single crystal bonding method will be useful for realizing high performance OLPFs