We report an image wavelength upconversion system. The system mixes an incoming image at around 1550 nm (eye-safe region) illuminated by an amplified spontaneous emission (ASE) fiber source with a Gaussian beam at 1064 nm generated in a continuous-wave diode-pumped ${\mathrm{Nd}}^{3+}\text{:}{\mathrm{GdVO}}_4$ laser. Mixing takes place in a periodically poled lithium niobate (PPLN) crystal placed intra-cavity. The upconverted image obtained by sum-frequency mixing falls around the 631 nm red spectral region, well within the spectral response of standard silicon focal plane array bi-dimensional sensors, commonly used in charge-coupled device (CCD) or complementary metal–oxide–semiconductor (CMOS) video cameras, and of most image intensifiers. The use of ASE illumination benefits from a noticeable increase in the field of view (FOV) that can be upconverted with regard to using coherent laser illumination. The upconverted power allows us to capture real-time video in a standard nonintensified CCD camera.

We study the field-of-view (FOV) of an upconversion imaging system that employs an Amplified Spontaneous Emission (ASE) fiber source to illuminate a transmission target. As an intermediate case between narrowband laser and thermal illumination, an ASE fiber source allows for higher spectral intensity than thermal illumination and still keeps a broad wavelength spectrum to take advantage of an increased non-collinear phase-matching angle acceptance that enlarges the FOV of the upconversion system when compared to using narrowband laser illumination. A model is presented to predict the angular acceptance of the upconverter in terms of focusing and ASE spectral width and allocation. The model is experimentally checked in case of 1550-630 nm upconversion.

We report generation of continuous-wave yellow laser radiation in a Nd³⁺-doped periodically poled lithium niobate bulk crystal. Simultaneous oscillation in pi polarization of the two infrared laser channels ⁴F_3/2 rarr⁴I_11/2 and ⁴F_3/2 rarr⁴I_13/2 of Nd³⁺ is achieved at 1084.4 and 1373.6 nm by end pumping with a Ti:Sapphire laser. Intracavity quasiphase-matched self-sum- frequency-mixing of both infrared laser waves in the poled crystal leads to the generation of yellow laser light at 606 nm. The yellow laser power obtained is 15.6 mW from an absorbed pump power of 314 in W.

We report a dual-wavelength continuous-wave laser at 542.4 and $546.8\mathrm{nm}$ based on an ${\mathrm{Nd}}^{3+}$-doped aperiodically poled lithium niobate crystal. Two fundamental infrared (IR) wavelengths at 1084.8 and $1093.6\mathrm{nm}$ are simultaneously oscillated and self-frequency-doubled to green. The aperiodic domain distribution patterned in the crystal allows for quasi-phase matched self-frequency-doubling of both IR fundamentals while avoiding their sum-frequency mixing.

We present an image upconversion system based on intracavity Type II second-harmonic generation to create an image in the visible spectrum of a target illuminated by an infrared laser. The system has the novelty of being self-illuminated. It uses some fractional leaking power of the infrared laser to illuminate a target located in the object focal plane of the system, and to couple back a created infrared target image to an intracavity nonlinear crystal, where it mixes with the cavity laser beam to obtain a second-harmonic image, visible with a silicon CCD camera. For a proof of concept, we have built a system based on a diode-pumped ${\mathrm{Nd}}^{3+}\text{:}{\mathrm{YVO}}_4$ continuous-wave (cw) laser and an intracavity KTP crystal to upconvert 1342 nm target images to 671 nm. The upconverted cw power allowed us to capture real-time video in a standard nonintensified CCD camera, with 2.5 W of a diode pump.