Improvement in active wavelength conversion to the visible of images illuminated in the SWIR by an ASE source

Abstract

We present an experimental system for active image wavelength conversion to the visible spectral region from the illumination of targets with sources in the short wavelength infrared (SWIR) spectral region centered at 1550 nm. Furthermore, a significant improvement of converted images in terms of field of view and resolution is demonstrated when an illumination source based on amplified spontaneous emission (ASE) is used instead of a laser in the proposed conversion system. The system is based on the nonlinear optical frequency mixing in a periodically poled lithium niobate (PPLN) crystal placed inside a diode-pumped Nd³⁺:GdVO₄ laser cavity. The up-converted image falls at 631 nm in the visible region as a result of the sum frequency mixing between the laser wave at 1064 nm and the SWIR wave resulting from the illumination of targets with ASE and laser sources in the vicinity of 1550 nm. This system also presents the advantage of providing images in the spectral region where CMOS and CCD standard silicon cameras are available with useful speed, efficiency, resolution and cost features.

References