Photonics Research, Volume. 7, Issue 7, 783(2019)
Mid-infrared upconversion imaging using femtosecond pulses
Fig. 1. Schematic of the experimental setup used for mid-IR femtosecond upconversion imaging. HWP, half-wave plate; PBS, polarizing beam splitter; OPO, optical parametric oscillator; BC, beam combiner; LN, lithium niobate crystal; MgO:PPLN, magnesium oxide-doped periodically poled LN crystal;
Fig. 2. Illustration of various angles used in the calculations. Description of different lines used is included in the figure.
Fig. 3. Calculation of
Fig. 4. Comparison of experimental and theoretical values of
Fig. 5. Illustration of upconverted intensity as a function of (a) mid-IR input angles and (b) mid-IR wavelengths. The FWHM of the intensities in (a) and (b) provides the angular and spectral acceptance bandwidth, respectively, for the upconversion process. The choice of
Fig. 6. Resolvability of the upconversion system. The USAF resolution target (top left) with green encircled portion indicates the region of the target that is upconverted; the upconverted image of the highlighted portion is at the top right. The intensity plot along a vertical strip (blue line) from the upconverted image is shown at the bottom. This strip contains the smallest feature of the target, and its corresponding intensity profile is enclosed within the green dotted ellipse.
Fig. 7. Illustration of chromatic blurring for broadband mid-IR light and a broad nonlinear acceptance bandwidth. (a) is a vectorial representation of the chromatic blurring effect. (b) shows the effect of a cone of incoming infrared angles being transferred as a blurred cone in the image plane. IP, image plane.
Fig. 8. Illustration of the net blurring effect. (a) shows the upconverted image. The dotted yellow circle shows the uncertainty of the collinear point. The four numbered sections correspond to four different locations in the image whose intensity versus pixel plot along the red and blue lines is given at the bottom. Red corresponds to tangential features, whereas blue corresponds to radial features with respect to the center. One pixel in the camera corresponds to
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Ashik A. S., Callum F. O’Donnell, S. Chaitanya Kumar, M. Ebrahim-Zadeh, P. Tidemand-Lichtenberg, C. Pedersen. Mid-infrared upconversion imaging using femtosecond pulses[J]. Photonics Research, 2019, 7(7): 783
Category: Nonlinear Optics
Received: Mar. 26, 2019
Accepted: May. 27, 2019
Published Online: Jun. 21, 2019
The Author Email: Ashik A. S. (ashas@fotonik.dtu.dk)