Electrically actuated phase-change pixels for transmissive and reflective spatial light modulators in the near and mid infrared.

Abstract

Transmissive and reflective spatial light modulators have been designed and simulated for the 1.55 to 2.10 μm spectral region. An electrically actuated layer of phase-change material (PCM) was employed as the electro-optical medium for two-state self-holding "light-to-dark" intensity modulation of free-space light beams. The PCM was sandwiched between transparent conductive N-doped Si or indium tin oxide contact layers in a simple planar structure. A 100 to 500 nm PCM layer of Ge2Sb2Te5 (GST) was employed for optimum performance at 1.55 μm where the transmissive-modulator insertion loss was around 4.5 dB. The GST light-dark contrast was found to be 32 dB. For the GST reflection device, an included metal film (Ag) improved the 1.55 μm performance metrics to 0.7 dB of insertion loss with a contrast around 26 dB. The calculated performance for both types of spatial light modulators was robust to changes in the input incidence angle near normal incidence. Applications include infrared scene generation and signal processing.