Mid-IR waveplate WP-ZO series

quartzdual-wavelengthzero order

Waveplates are used to manipulate polarization. It’s done by retardation in the birefringent crystal. When the electrical field is aligned at 45 degrees to the optical axis of the waveplate, extraordinary polarization faces retardation compared to the ordinary and phase delay occurs. Depending on the thickness of the waveplate retardation could be 180 deg, 90 deg or any other. When retardation is 180 deg, polarization direction changes by 90 deg and it’s called λ/2 waveplate. In the case of 90 deg phase retardation, we have circular polarization, and it’s called λ/4 waveplate. However, any other retardation could be realized by choosing the proper thickness of the waveplate. Waveplates could be made in various configurations. One of the most common configurations is zero order, when two crystalline quartz plates are optically contacted with the crossed optical axis. The alternative is zero order air-spaced configuration where crystalline quartz plates are mounted in special holders with the spacer between them. In both cases, zero order configuration allows to have designed retardation for more than 20 nm wavelength bandwidth. For long pulse applications and when the laser power is less than tens of watts, multi-order configuration of the waveplate could be used. In such configuration, crystalline quartz waveplate is a single plate with a typical thickness of ~1 mm. Crystalline quartz waveplates, regardless of the configuration, are coated with antireflection coatings. The coatings reduce reflection from one surface down to < 0.2 %, however if the highest transmission needs to be reached, IBS coatings could be used achieving reflection values < 0.1 %.