The U.S. Air Force Research Laboratory – Sensors Directorate (AFRL RY) has developed a patent pending, universal polarization converter capable of converting unpolarized light into pure polarized light of any kind with 100% efficiency. The AFRL invention breaks the physics Law of Malus which states that the maximum conversion efficiency of unpolarized light into polarized form cannot exceed 50%. Achieving 100% conversion enables the size of polarization sensitive optical systems to be dramatically reduced, resulting in significant savings in both weight and cost.
Applications for the polarization converter are numerous and include laser polarization conversion, coherent beam combination, sensor enhancement and protection, television and liquid crystal display (LCD) brightness improvement, wavelength division multiplexer loss reduction, optical switches, optical filters, LIDAR sources, radar sources, and improved antenna designs. Using a prototype configuration, the polarization converter has demonstrated near 100% conversion efficiency for both coherent and incoherent sources with 99.5% efficiency demonstrated for a low power (1-25mW) He-Ne laser and 100% efficiency achieved for a 5 mW superluminescent diode (~10nm bandwidth). The polarization converter is currently being evaluated for use with high power (>100W) fiber laser systems with early results indicating 100% efficiency should be attainable.
The polarization converter may be realized in several embodiments, with optical components and configurations varying according to the specifications of the light source (bandwidth, power, etc). The optical components employed in various configurations include liquid crystal cholesteric mirrors, quarter and half wave plate retarders, polarizers, and cycloidal diffractive waveplates. In one embodiment, a simple, “mono-block” device was designed which utilizes a single polarized converter in conjunction with three quarter wave plates to achieve 100% conversion efficiency in a compact form-factor.
- 100% conversion efficiency: Optical systems incorporating the universal polarization converter can achieve up to a 2x increase in performance relative systems which employ conventional polarizers
- Coherency agnostic: Near 100% conversion efficiency has been achieved for both coherent and incoherent light sources
- Widespread applicability: The universal polarization converter provides critical enhancement for a wide range of applications including: increasing power of fiber lasers for machining, increased brightness of LCDs with decreased power consumption, coherent beam combination, and improved antenna and satellite communications
- US patent application 20160131920A1 is available for license and commercialization
- Potential for collaboration with AFRL/RY researcher