Parallel Polarization State Generation

Abstract

The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

Spin-Orbit Interactions of Light: Fundamentals and Emergent Applications

“…Appropriate nanoantenna designs can be engineered to produce the calculated Jones matrix. Metasurfaces have been used to convert between linear and circular polarizations, between various linear polarization states, and between opposing circular polarization states [32,33,34]. Because circularly polarized input light is one of geometric-phase metasurfaces main limitations, it is necessary to precisely match the geometric phase to the propagation phase in order to obtain unrestricted control of polarization states.…”

“…In order to create optical vortex beams with net topological charge or OAM of light (l), polarization-control in metasurfaces that permit manipulation of the propagation phase and the geometrical phase can also be used [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. The helixed wave front of such OAM beams, which is a direct result of the dependence of phase on azimuthal angle, is one of its most distinctive features.…”

Spin-Orbit Angular Momentum Conversion in Metamaterials and Metasurfaces

“…The calculated Jones matrix can be achieved by engineering proper nanoantenna patterns. Up to now, conversion between a linear polarization and a circular polarization, between different linear polarization states or between opposite circular polarization states have been reported using metasurfaces [44,42,43]. Geometrical phases can be generated by engineering the metasurface with identical nanoantennas of spatially varying orientations, as described in Section 1.…”

“…On the other hand, metasurfaces can create helical wave fronts by arranging nanoantennas with linearly increasing (or decreasing) phase shifts along the azimuthal direction [59,60,61,62,63,64,65,25]. As a result, a metasurface can add an optical vortex to the incident light wave front, thus converting SAM into OAM, this transformation is also termed spin-to-orbit conversion (SOC) [66,67,44,42,43]. Normally the SOC permits only the conversion of LHC and RHC polarization into states with opposite OAM, due to conservation of total angular momentum (TAM).…”

“…OAM division multiplexing is an experimental method for increasing the transmission capacity of electromagnetic signals using the OAM of the electromagnetic waves to distinguish between the different orthogonal channels [46]. It is the analogue of wavelength division multiplexing (WDM), time division multiplexing (TDM) or polarization division multiplexing (PDM) [71,43], in the subspace spanned by OAM of light. While SAM) or polarization multiplexing offers only two orthogonal states corresponding to the two states of circular polarization, OAM multiplexing can access a potentially unbounded set of states and as such can offer an infinite number of channels for multiplexage.…”