High Contrast Polarizers For The Near Infrared.

Corning has extended the performance of its PolarcorTm near infrared glass polarizers to contrast ratios k1 /k2 of over 10,000. These polarizers offer broader bandwidth, higher transmittance, higher temperature resistance, better durability, and improved contrast (extinction) when compared to plastic and wire grid polarizers. Acceptance angle, cost, and compactness are significantly better than crystal polarizers. Applications include optical isolators, Faraday rotators, magneto-optic devices, fiber optic sensors, Kerr effect devices and optical data storage devices. Polarcor contains elongated, submicron silver metal particles aligned along a common axis. These particles preferentially absorb the polarization component of light which is aligned with the elongation axis of the particles. The mechanism is believed to be resonant absorption by the silver conduction electrons. Careful process control allows the polarizer performance to be optimized at various laser lines, although a wide bandwidth provides polarization over a range of wavelengths. The polarization results from a very thin layer on the surface of the polarizer, thus allowing high contrast from a very thin package. Recent advances in processing have resulted in increases in the contrast ratio from 500 to over 10,000 while maintaining k1 values of 87-91%, depending on wavelength. The corresponding values of Ho and Hgo are 38-41% and 7.6-8.5x10-5, respectively. Performance may be improved by application of high efficiency anti-reflective coatings. This paper reports on a characterization study of the performance of newly developed Polarcor high contrast polarizers optimized for applications from 725-1550 nm.