Microintegrated optical isolators for visible wavelengths for space application

In order to use single frequency lasers in practical applications with demanding requirements on frequency stability, optical isolators are essential components. The availability of single frequency laser diodes in the visible wavelength region enables the design of micro-integrated laser systems and likewise led to a demand for suitable micro-integrated optical isolators for visible wavelength, e.g. for micro-integrated ECDL laser and MOPA modules. Unlike for the near infrared, micro-integrated optical isolators for the wavelength region between 680 and 1000 nm are not available so far, limiting or even hindering use of micro-integrated laser sources for space mission with photonic, spectroscopic and quantum-technological mission payloads. To overcome this issue, a micro-optical isolator for space application for visible wavelengths has been developed. The design specifically features a low stress crystal mount with a symmetric heat removal essential for good isolation, the avoidance of beam deflection, and a large allowable temperature range. Moreover, the high homogeneity of the magnetic field enables at least 40dB single stage isolation, limited by polarizers and crystal properties. Structural and thermo-elastic analyses have been performed to ensure a space qualifiable design. The delicate micro-integration of the optical isolator has been established at STI. The isolator design as well as preliminary results obtained during integration will be presented. The space qualification program of the microisolator will be introduced.