The integration of optical thin film filters by hydrofluoric acid bonding

A hydrofluoric acid (HF) bonding method has been applied for the thin film filters integration. The quality of bonding was examined by the evaluation of bonding strength and the observation of bonding interface. The bonding strength depends on the applied pressure and temperature during bonding. The maximum bonding strength was more than 10 MPa. High quality bonding interface was observed by scanning electron microscope and transmission electron microscope. A color filer array of red, green and blue (RGB) was designed to separate the white light. The filters were integrated into a glass body successfully by HF bonding. Its transmittance spectra were unchanged after heating at 450oC for 20 hours. In addition, integration of filters was carried out to fabricate an optical demutiplexer for coarse wavelength division multiplexing system. It was confirmed that the integrated filter array acted as a demutiplexer.