Polarizer

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Polarizer

Union Optic provides the following polarizers with four materials include a-BBO, Calcite, Quartz and YVO4 for widest spectrum and high polarization application.

Polarizer	Material	Illustration	Properties and Application
Glan-Taylor Polarizer	a-BBO(190-3500nm) Calcite(350-2300nm) YVO4(500-4000nm)		Air-spaced Close to Brewster's Angle cutting For medium power application
Glan-Laser Polarizer	a-BBO(190-3500nm) Calcite(350-2300nm) YVO4(500-4000nm)		Air-spaced. Close to Brewster's angle cutting Mounted with escape window Suitable for high power applications
Glan-Thompson Polarizer	Calcite(400-2300nm)		Cemented Suitable for low power applications Wide acceptance angle
Brewster Polarizer	Calcite(350-2300nm) YVO4(500-4000nm)		Transmission Efficiency T>98% High damage threshold No AR coating needed
Wollaston Polarizer	Calcite(400-2300nm) YVO4(500-4000nm) Quartz(400-2300nm)		Cemented Separate ordinary and extraordinary beams at certain angle Suitable for low power application and where the large deviation is required
Rochon Polarizer	YVO4(500-4000nm) Quartz(400-2300nm)		Cemented Split the ordinary and extraordinary ray, but only ordinary beam is deviated Suitable for low power application
Polarization Beamsplitter Plate	BK7		Split the S beam and P beam Brewster angle of incidence Suitable for high power apolication
Polarization Beamsplitter Cube	BK7, SF glass		Split the S beam and P beam
Polarization Rotator	Quartz		Rotate polarization state
Optical Isolator	BK7, Quartz		Block optical feedback Passive isolation of linearly polarized light High isolation
Lateral Displacement Polarization Beamsplitter	BK7		Split incident beam into two displaced parallel beams Waveplate can be added to manage polarization state NOA61 cemented
Depolarizer	Quartz		Eliminate polarization effect

Comparison of the four materials

	YVO4	Calcite	a-BBO	Quartz
Transparency	500-4000nm	350-2300nm	200-3500nm	200-2300nm
Crystal Class (Uniaxial)	Positive no=na=nb,ne=nc	Negative no=na=nb,ne=nc	Negative no=na=nb,ne=nc	Positive no=na=nb,ne=nc
Mohs Hardness	5	3	4.5	7
Thermal Expansion Coefficient	aa=4.43x10^-6/K ac=11.37x10^-6/K	aa=24.39x10^-6/K ac=5.68x10^-6/K	aa=4x10^-6/K ac=36x10^-6/K	aa=6.2x10^-6/K ac=10.7x10^-6/K
Hygroscopic Susceptibility	Low	Low	Low	Low

Note:

Classic Glan Laser type prisms (PGT, PGM, and PGL Series) suffer a small, unavoidable loss at the two internal calcite-air interfaces. This loss is avoided in the Brewster type (PBI Series) by presenting the P polarized transmitted beam to these interfaces at Brewster's angle. The result is a high power, low loss polarizer that does not need AR coating.

The user should be aware of two important considerations in the use of Brewster Polarizer (PBI polarizers). First, stringent angular acceptance requirements dictate use with collimated beams only. Second, the transmitted beam has a relatively large parallel beam displacement with respect to the incident beam.