Antireflection Microstructured Surface on ZnSe for Mid-infrared Spectral Region

Abstract

Antireflection microstructured surface were fabricated on ZnSe through a rapid and scalable method which was called femtosecond laser direct writing (FsLDW). With this technology, micrometer level inverted pyramid and cone arrays were fabricated precisely. The measured transmittance were about 11.3% higher compared with the plain ZnSe at 9μm in the ideal situation. These results were in good accord with the simulations which were calculated by geometric and diffractive field tracing techniques.

Preparation of Antireflection Microstructures on ZnSe Crystal by Femtosecond Burst Bessel Direct Laser Writing

“…Fabricating an antireflection microstructure (ARM) on the surface is a different alternative method to increase surface transparency [11,12]. ARMs, which can significantly reduce Fresnel loss, can be prepared mainly by direct imprinting [13][14][15], dry or wet etching [16][17][18][19][20][21], laserinduced periodic surface structures [22][23][24], and direct laser ablation [25][26][27][28][29][30][31][32][33]. Among the conventional methods, the critical advantage of direct laser ablation is that the fabrication method is straightforward, and ARMs can be prepared on most materials.…”

“…Moreover, a few additional steps and materials are required during direct laser ablation, significantly reducing the production costs. Nowadays, many research groups have applied direct laser ablation to ZnSe [25,26], ZnS [27][28][29][30][31] and other materials [32,33] to fabricate ARMs. M.K.…”

“…Tarabrin et al reported the demonstration of ZnSe single crystal reflectivity reduction of up to 3% in a spectral range of 3.5 to 15 µm by using femtosecond laser pulses for microstructure formation without employing any etching technique [26]. Jia et al fabricated micrometer-level inverted pyramid and cone arrays on ZnSe through femtosecond laser direct writing, and the measured transmittance was about 11.3% higher compared with that of plain ZnSe at 9 µm in an ideal situation [25]. When the period of the ARM is much smaller than the wavelength, the microstructure can be equivalent to a multilayer of the thin film medium.…”

“…Hence, transmittance is determined by the morphological parameters of ARM [2]. Some articles have reported the influence of different shapes and craters on ARMs' performance [25,28], but a few papers have reported using femtosecond laser burst mode to prepare ARMs. In addition, laser burst mode operation can improve the ablation rates in semiconductors and dielectrics [34].…”

High-Transmission Biomimetics Structural Surfaces Produced via Ultrafast Laser Manufacturing

“…Moreover, the flexibility of ARSS design is enhanced by various parameters, such as period, shape, fill factor and depth [29]. To date, many approaches have been proposed to prepare ARSSs, including photolithography [30,31], nanoimprinting [32], electron beam lithography [33,34], plasma etching [35][36][37][38], the solgel method [39], the self-assembly method [40] and laser processing [41][42][43][44]. However, there are still some limitations to be addressed, such as expensive equipment, complex manufacturing processes and inability to control the etching process.…”