Plasmonics-based GaAs metal-semiconductor-metal photodetector (MSM-PD) with aluminum nano-gratings was proposed. A detailed numerical study of subwavelength nanogratings behavior to reduce the light reflection is performed by finite-difference time domain (FDTD) algorithm. The geometric parameters of nano-gratings, such as aperture width, the nano-gratings height, the duty cycles are optimized for subwavelength metal nanogratings on GaAs substrate and their impact on light reflection below the conventional MSM-PD is confirmed. Simulation results show that a light reflection factor around 15% can be obtained near the wavelength of 900 nm with optimized MSM-PDs, and in visible light spectrum, the Al nano-gratings show better performance than Au nano-gratings.
A method for holographic femtosecond laser parallel processing is proposed, which can suppress the interference of zero-order light effectively and improve the energy utilization rate. In order to blaze the target pattern to the peak position of zero-order interference, a phase-only hologram containing a digital blazed grating is designed and generated, and the energy of the target pattern can be increased by 3.793 times in theory. In addition, by subsequently increasing the phase of the divergent spherical wave, the focal plane of the target pattern and the plane of the multiorder diffraction beam resulting from the pixelated structure of the spatial light modulator (SLM) can be separated. Both a high-pass filter and aperture are used to simultaneously eliminate the influences of zero-order light and multiorder interferential patterns. A system based on the phase-only SLM (with resolution of 1920×1080) is set up to validate the proposed method. The experimental results indicate that the proposed method can achieve high-quality holographic femtosecond laser parallel processing with a significantly improved energy utilization rate.
A novel method for holographic femtosecond laser parallel processing is proposed, which can suppress the interference
of zero order light effectively and improve the energy utilization rate. In order to blaze the target pattern to the peak
position of zero-order interference, a phase-only hologram containing digital blazed grating are designed and generated,
The energy of the target pattern can be increased to 5.297 times in theory. In addition, by subsequently increasing the
phase of divergent spherical wave, the focal plane of the target pattern and the plane of multi-order diffraction beam
resulted from pixelated structure of the spatial light modulator (SLM) can be separated. Both the high pass filter and
aperture are used to eliminate the influences of zero-order light and multi-order interferential patterns simultaneously. A
system based on the phase-only SLM (with resolution of 1920*1080) is set up to validate the proposed method. The
experimental results indicate that the proposed method can achieve high quality holographic femtosecond laser parallel
processing with a significantly improved energy utilization rate.
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