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1. Plasma Gratings at kHz Repetition Rate for High-Power Lasers

   https://doi.org/10.1364/CLEO_FS.2026.FM1B.3  

   Wang, MM; Perez-Ramirez, VM; Singh, D; Das, A; Mason, MF; Tigges-Green, I; Dewan, V; Michel, P; Edwards, MR; Mikhailova, JM (January 2026, Optica Publishing Group)

   We experimentally generate an ionization plasma grating at 1 kHz repetition rate and demonstrate diffraction stability over one hour of operation without significant performance degradation. 

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2. Plasma-Grating-Enabled Second Harmonic Generation

   https://doi.org/10.34133/ultrafastscience.0131  

   Fu, Shing Yiu; Yuan, Daopeng; Zhang, X-C (January 2026, Ultrafast Science)

   We present the experimental features of second harmonic emission from an air plasma coexcited by 2 ultrafast laser pulses and propose a theoretical model that describes the observed properties. The dual-beam optical nonlinear process was discovered to depend on the optical polarization of both fundamental pulses simultaneously, and the output emissions coincided with the propagation directions of the 2 input laser beams. These attributes of the ultrafast phenomenon are reconciled by incorporating the action of plasma grating into the interaction picture. When the diffractive property of the laser-induced grating is considered, each of the fundamental beams is diffracted onto the direction of the other. The collinear fundamental components can then generate a second harmonic radiation that fulfills the phase matching condition. The ensuing theoretical simulation fits well against the experimental observations. Finally, we analyze the effective nonlinear susceptibility tensor of the air plasma to facilitate future research on the hidden symmetries within plasmas induced by intense ultrafast lasers. 

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3. Optimization of Diffraction Efficiency for Ionization-Induced Plasma Gratings

   https://doi.org/10.1364/CLEO_FS.2024.FW3C.8  

   Wang, M M; Fasano, N M; Perez-Ramirez, V M; Giakas, A M; Ou, K; Cao, S; Michel, P; Mikhailova, J M; Edwards, M R (May 2024, Optica Publishing Group)

   A plasma grating is generated by temporally crossing and interfering two femtosecond beams to create modulated ionization. We achieve maximum Bragg diffraction efficiency of 35% by tuning grating transverse size, length, and incident beam configurations. 

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4. Multiple-aperture grating pattern inscription engine: UV pattern lithography tool for reactive ion-plasma etched large diffraction gratings and beyond

   https://doi.org/10.1117/12.3101067  

   Lee, Hanshin; Subash, Uma; Paudel, Samir; Poutous, Menelaos K; Smith, Michael P; Vattiat, Brian L (August 2026, SPIE)

   Navarro, Ramón; Jedamzik, Ralf (Ed.)

   As reported elsewhere, the Reactive Ion-PLasma Etched (RIPLE) grating technology emerged to show its highly predictive process that resulted in gratings with near theoretical super-broadband diffraction efficiency. The RIPLE process taps into electron-beam (eBeam) patterning and dry reactive-ion etching to embed a nano-scale grating structure into substrate material. Our prior NSF-supported effort succeeded in scaling the process in grating area to 4x4 sq. inch. However, our reliance on the commercially available eBeam services prevents the RIPLE process from scaling in area beyond 5x5 sq. inch. Under new NSF support, we began developing a dedicated large area grating patterning tool called the MAGPIE. It uses a long-travel nano-positioning stage and near-field Talbot effect to inscribe nano-scale grating patterns over very large areas. We discuss the operational principles, system/subsystem designs and prototyping activities so far, and some of the early tests of the MAGPIE. 

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5. Reactive ion plasma etched surface relief gratings for low/medium/high resolution spectroscopy in astronomy

   https://doi.org/10.1117/1.JATIS.8.4.045002  

   Lee, Hanshin; Poutous, Menelaos K (October 2022, Journal of Astronomical Telescopes, Instruments, and Systems)

   We report the fabrication of a binary-phase proof-of-concept astronomical diffraction grating embedded in a quartz substrate via reactive ion plasma etching. This grating operates at the first diffraction order within the 450 to 750 nm wavelength band. It features 1400-nm-deep, 188-nm-wide binary grooves at a 566-nm pitch, or 1767 lines/mm groove density, over a 25.4 × 25.4 mm2 area. A high depth-to-width ratio ( ∼ 8 ∶ 1 in this case) is one of the keys to near-theoretical diffraction efficiency being attained by the fabricated grating (94% at center wavelength and 70% at band edges) over a broad bandpass (>200 nm). This performance is also attributed to high-resolution micro-lithographic electron-beam patterning and anisotropic reactive ion etching process fabrication techniques. These types of binary gratings can potentially be high-throughput alternatives to Volume-Phase Holographic Gratings (VPHGs) for general spectroscopic applications. When scaled to appropriate sizes for astronomy, such gratings can serve as main or cross dispersion elements in low-, medium-, and high-resolution spectrographs not only in ground-based telescopes but also in those subject to challenging environmental conditions such as in space observatories. 

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