Polarization-sensitive Optical System Research Articles

Brillouin Scattering Selection Rules in Polarization-Sensitive Photonic Resonators.

Spontaneous Brillouin scattering in bulk crystalline solids is governed by the intrinsic selection rules locking the relative polarization of the excitation laser and the Brillouin signal. In this work, we independently manipulate the polarization of the two by employing polarization-sensitive optical resonances in elliptical micropillars to induce a wavelength-dependent rotation of the polarization states. Consequently, a polarization-based filtering technique allows us to measure acoustic phonons with frequencies difficult to access with standard Brillouin and Raman spectroscopies. This technique can be extended to other polarization-sensitive optical systems, such as plasmonic, photonic, or birefringent nanostructures, and finds applications in optomechanical, optoelectronic, and quantum optics devices.

A Mueller matrix approach to flat gold mirror analysis and polarization balancing for use in retinal birefringence scanning systems

In a polarization-sensitive optical system, it is important to understand the effects that mirrors have on polarization at a specific wavelength of interest, angle of incidence, reflective material, coating, etc. When modeling reflection, the optical designer oftentimes needs to know the Mueller matrix for the particular mirror, in order to assess its overall impact on polarization and possibly reduce the mirror-related effects in the entire system’s performance. Based on an example of a protected gold flat mirror, we investigated two methods, one analytical and one experimental, for determining the Mueller matrix of a noble metallic mirror. The measured Mueller matrix was shown to be nondepolarizing. Then, using polar decomposition, the measured matrix was interpreted as a combination of a pure retarder and a diattenuator. Further investigation showed that the diattenuation property was very weak, which offered the opportunity of largely balancing the introduced polarization deviation by means of a linear compensating retarder. The results of this work were used successfully for improving the design of a diagnostic device for ophthalmology based on retinal birefringence scanning. The described approach also greatly improves the precision of Mueller-matrix-based computer modeling of polarization sensitive systems.

A method of calculating compensators in polarization-sensitive optical systems

A simple method to measure and compensate polarization-sensitive optical components (retarders) is proposed, based on Stokes vector polarimetry. First, the Mueller matrix of an unknown polarization-sensitive element with arbitrary retardance and fast-axis orientation is obtained by means of a conventional measurement and calculation polarimetric procedure. Then a novel numerical technique is proposed, allowing to express the measured retarder’s Mueller matrix in terms of retardance δ and fast axis orientation θ. Further, a method for calculating polarization compensators is proposed, to balance phase differences introduced by one or more retarders. Compensation is achieved by a single compensating retarder whose parameters are derived from the original retarder’s Mueller matrix, or its equivalent (δ,θ) pair. The technique works for all possible fast-axis orientations of the original retarder. The method was validated using an electrically controllable liquid crystal retarder as a compensator. The approach described here is constrained to optical elements that behave as nearly pure retarders, i.e. their diattenuation and depolarization are negligible. Possible applications are in the design of polarization-sensitive systems (biomedical, environmental, chemical, optical communications, etc.) where recovery and/or precise control of the polarization state of light is needed, in polarization tracing models based on the Mueller matrix formalism, and others.

Three-dimensional polarization algebra for all polarization sensitive optical systems.

Using three-dimensional (3D) coherency vector (9 × 1), we develop a new 3D polarization algebra to calculate the polarization properties of all polarization sensitive optical systems, especially when the incident optical field is partially polarized or un-polarized. The polarization properties of a high numerical aperture (NA) microscope objective (NA = 1.25 immersed in oil) are analyzed based on the proposed 3D polarization algebra. Correspondingly, the polarization simulation of this high NA optical system is performed by the commercial software VirtualLAB Fusion. By comparing the theoretical calculations with polarization simulations, a perfect matching relation is obtained, which demonstrates that this 3D polarization algebra is valid to quantify the 3D polarization properties for all polarization sensitive optical systems.