Torregrosa Adrián J, Karamehmedović Emir, Maestre Haroldo, Rico María Luisa, Capmany Juan
Communications Engineering Department and I3E, Universidad Miguel Hernández, Avda. de la Universidad s/n, 03202 Elche, Spain.
Faculty of Engineering and Natural Sciences, International University of Sarajevo, Hrasnička cesta 15, 71210 Sarajevo, Bosnia and Herzegovina.
Sensors (Basel). 2020 Jun 26;20(12):3610. doi: 10.3390/s20123610.
Up-conversion sensing based on optical heterodyning of an IR (infrared) image with a local oscillator laser wave in a nonlinear optical sum-frequency mixing (SFM) process is a practical solution to circumvent some limitations of IR image sensors in terms of signal-to-noise ratio, speed, resolution, or cooling needs in some demanding applications. In this way, the spectral content of an IR image can become spectrally shifted to the visible/near infrared (VIS/NWIR) and then detected with silicon focal plane arrayed sensors (Si-FPA), such as CCD/CMOS (charge-coupled and complementary metal-oxide-semiconductor devices). This work is an extension of a previous study where we recently introduced this technique in the context of optical communications, in particular in FSOC (free-space optical communications). Herein, we present an image up-conversion system based on a 1064 nm Nd: YVO solid-state laser with a KTP (potassium titanyl phosphate) nonlinear crystal located intra-cavity where a laser beam at 1550 nm 2D spatially-modulated with a binary Quick Response (QR) code is mixed, giving an up-converted code image at 631 nm that is detected with an Si-based camera. The underlying technology allows for the extension of other IR spectral allocations, construction of compact receivers at low cost, and provides a natural way for increased protection against eavesdropping.
基于红外（IR）图像与本地振荡器激光束在非线性光学和频混频（SFM）过程中的光学外差的上转换传感，是在某些苛刻应用中规避红外图像传感器在信噪比、速度、分辨率或冷却需求方面的一些限制的切实可行的解决方案。通过这种方式，红外图像的光谱内容可以在光谱上移至可见光/近红外（VIS/NWIR），然后用硅焦平面阵列传感器（Si-FPA）进行检测，例如电荷耦合器件（CCD）/互补金属氧化物半导体器件（CMOS）。这项工作是先前一项研究的扩展，在先前的研究中，我们最近在光通信的背景下，特别是在自由空间光通信（FSOC）中引入了这项技术。在此，我们展示了一种基于1064 nm Nd:YVO固态激光器的图像上转换系统，其腔内有一块磷酸钛氧钾（KTP）非线性晶体，在其中将一束用二进制快速响应（QR）码进行二维空间调制的1550 nm激光束进行混频，产生一个631 nm的上转换编码图像，该图像由基于硅的相机进行检测。这项基础技术允许扩展到其他红外光谱分配，以低成本构建紧凑型接收器，并为增强防窃听保护提供了一种自然的方式。
