Birefringent Filter Plates

The birefringent filter plate is a linear retarder made of crystalline quartz and used intracavity to selectively tune a desired wavelength and create reflection losses at other wavelengths. In use, it is placed at Brewster’s angle, and then rotated about the axis perpendicular to the surface to achieve a full wave retardation at the wavelength of interest. The selected wavelength contains only a p-polarization component, and thus experience no reflection loss. Other wavelengths undergo a different retardation, and have some amount of s-polarization, leading to reflection losses.

A typical birefringent filter contains a stack of 2–4 quartz  plates, each plate being half the thickness of the previous one. The thickest plate sets the bandwidth and the thinnest the free spectral rang (FSR).

Standard Birefringent Filter Plates

Newlight  can produce a wide variety of custom BIRs for your specific applications. Please contact us for assistance with your requirements.

Mount

BIRs with diameter =< 15mm may be mounted in stack with air space in a 1" anodized aluminium holder. Larger BIRs may be mounted in a 1.25" (31.8mm) or 1.5" (38.1mm) holder.

Specifications