Spectral response of a thermal-image converter

Upconversion of Broadband Infrared Radiation into Visible Light for Different Pumping Parameters

“…Moreover, the conversion efficiency of broadband infrared radiation depends on the thermal object temperature and the pump radiation parameters [9]. The increase in the thermal object temperature has very little effect on changing the experimental spectrum shape (Figure 2(b)), while the conversion efficiency is increased (Figure 3(b)).…”

“…where is a constant proportional to the squared component of the nonlinear susceptibility tensor, 1 ( 1 ) and 2 ( 2 ) are the intensities of interacting light waves, is the length of a crystal along the propagation directions of waves, and Δ is the disturbance of phase matching. The disturbance of phase matching is given as [8][9][10][11][12][13]…”

“…The intensity of the converted broadband radiation with frequency 3 is provided by the resulting interaction of waves of all frequencies 1 and 2 that are equidistant from 3 /2. The spectral intensity ( 3 ) for a collinear light beam is given as [8][9][10]…”

“…where , and are refractive indexes for ordinary and extraordinary waves at the respective frequencies. The intensity of the converted broadband radiation at the crystal output was calculated by taking into account the interactions of noncollinear light beams along all possible directions within the angle range of an input convergent beam of infrared broadband radiation [9][10][11][12]:…”

“…The influence of thermal object temperature and pump radiation parameters on the spectrum and conversion efficiency of broadband infrared radiation has been investigated [8][9][10]. In these studies, the spectra of converted infrared radiation were calculated for collinear light beams.…”