Light-controlled photonics-based mm-wave beam switch

Abstract

We present experimental investigation of light-controlled photonics-enhanced quasi-optical mm-wave beam switch operating at a resonant frequency in the mm-wave band of 75 to 110 GHz. The switch is implemented as a Bragg structure with a resonant layer of high-resistivity silicon that creates a narrow transmission peak within the mm-wave propagation gap. The peak amplitude is sensitive to the intensity of light pulses illuminating the structure. When using a silicon wafer of 30 KOhm · cm resistivity and light pulses created by a 400W LED-array light source, we achieved mm-wave transmission peak modulation exceeding 15 dB.

Mm-Wave Dielectric Parameters of Magnesium Fluoride Glass Wafers

“…The bench is furnished with custom split-step dual-aspheric MM-wave Fresnel lenses [13] which refocus nearly Gaussian beams of conical corrugated horns [14] fed by the VNA heads as shown in Figure 2(b) in [15]. The lenses create near-Gaussian beams of the waist radius w A = 24 mm at the aperture of stainless-steel holder carrying a Bragg structure inside (the aperture radius is R A = 34 mm) [15]. The axial positions of the VNA heads and lenses z n (n = 1−4, Figure 1) were computer controlled using Zaber linear actuators.…”

“…(1) beam incident on the aperture of (a) an empty holder and (b) a holder with an absorber (reference data), (2) a single MgF 2 wafer fixed in the holder (m1 structure), and (3) a Bragg structure of 5 MgF 2 wafers with 4 air spaces of thickness a = 0.102 mm (4ma − m structure). earlier measurements [15] where spectral curves for the comparison with simulations were taken at the fixed positions of quasi-optical components. The development increases the accuracy of the technique that makes it possible to use the method for characterization of ultra-low-loss dielectric materials.…”

“…Simulations of MM-wave propagation through multi-layer structures are based on the plane-wave transmission matrix approach [15,16] extended for spatially-limited vector electromagnetic beams. Plane-wave transmission matrix simulations are straightforward.…”

“…Available MgF 2 wafers are not suitable for making structures of this type, but when being used as the defect layers in the quartz-based assemblies as those in [15], they produce transmission spectra as required (Figures 12 and 13). Because of different materials, many layers, and uncertainty of each layer thickness, the estimate of material dielectric constant in these structures is less reliable.…”

Method of measuring non-equilibrium carriers concentration and their lifetime in a semiconductor using the approach of a photonic crystal with a defect mode

“…For this reason the structures from dielectrics and ferrites are used [3]. The presence of semiconductor layers in PCs should make it possible to control spectral properties by using the external effects like temperature [4], illumination [5], and injection of inhomogeneities in a semiconductor layer [6]. It is necessary to use semiconductors to create light controllable PCs [7], because there is photoconductivity in the semiconductors.…”