Wide bandgap photoconductor (SiC:V)-based optically addressed light valve for high fluence operation

Journal Article · Mon Mar 17 00:00:00 EDT 2025 · Applied Optics

DOI:https://doi.org/10.1364/ao.540656· OSTI ID:2553127

Chatterjee, Bikramjit ^[1]; Ghandiparsi, Soroush ^[1]; Gottlieb, Miranda S. ^[1]; Shao, Qinghui ^[1]; Frye, Clint D. ^[1]; Harrison, Sara ^[1]; Voss, Lars ^[1]

---

1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Optically addressable light valves based on wide bandgap 4H- and 6H-SiC as photoconductors were designed to withstand higher operational laser fluences than the state of-the-art bismuth silicon oxide (BSO; Bi₁₂SiO₂₀) based devices. Vanadium-doped SiC was selected as the photoconductors due to their reasonable photoresponsivity while many fold improvement in laser induced damage threshold as compared to BSO. The laser induced damage threshold values of the materials were measured after exposing ~ 200 sites on the samples to increasing levels of fluence of a gaussian pulsed Nd: YAG laser system (1064 nm) with a 5 Hz repetition rate. The measured damage threshold values for BSO, 4H- and 6H-SiC were 0.4 J/cm², 1.75 J/cm² and 1.8 J/cm², respectively. Photoconductive switches based on 4H and 6H-SiC samples were characterized at wavelengths of 380 nm, 405 nm, and 447 nm. The peak photoresponsivity values of the 4H- and 6H-SiC materials were measured to be under 380 nm and 405 nm, respectively. The photoconductor was bonded to a BK7 optical window with 5 μm diameter microspheres as spacers. A twisted nematic type E7 liquid crystal (LC) was filled in the 5 μm gap in a vacuum chamber. The desired alignment of the liquid crystal was achieved by mutually orthogonal orientation of LC alignment layers on the two mating faces (SiC and BK7). The fabricated devices were modulated using address beams of wavelengths 380 nm, 405 nm, and 447 nm. In conclusion, required transmission levels of > 90% was achieved for the fabricated OALVs for a sinusoidal voltage waveform that meets the lifetime requirement of the device.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2553127
• Report Number(s): LLNL--JRNL-862443; 1094174
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 10 Vol. 64; ISSN 1559-128X
• Publisher: Optical Society of America
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
70 PLASMA PHYSICS AND FUSION TECHNOLOGY