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 investigate the use of dual-wavelength laser illumination in a nonlinear infrared-to-visible image upconversion system. We show how a two-wavelength laser illumination can combine the enhanced upconversion field-of-view (FOV) characteristic of broadband thermal or amplified spontaneous emission (ASE) illumination with the higher power intensity of a laser. By properly choosing the wavelength spectral spacing of only two laser wavelengths and their relative amplitudes, the FOV that can be upconverted in the nonlinear crystal can be enlarged up to an extent similar to broadband illumination and intensity homogenized. In this way, a step is taken towards image upconversion beyond the lab to practical longer range illumination-assisted outdoor applications. We provide an experimental verification in good agreement with our model's simulations for original infrared images in the eye-safe spectral region around 1550 nm upconverted to around 631 nm in a periodically poled LiNbO $_{3}$ crystal.

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.

A design of chirped fiber Bragg gratings (CFBGs) for the compensation of higher order dispersion in dispersive delay lines of microwave photonic (MWP) filters driven by broadband sources is presented. It is shown that the modification of the dispersion slope of a nonlinearly CFBG can compensate for third-order dispersion in relatively broad optical bands, resulting in a linear correspondence between group delay and optical frequency. The concept is demonstrated by use of a custom modification of a commercial, low-ripple CFBG for dispersion compensation in 20 nm of the C-band. This broadband linear dispersive delay line is used to provide shape invariance in both the resonance's amplitude and phase responses of single-passband MWP filters based on double-sideband modulation. The dispersion of the delay line is shown to be tunable in the range -170.0 to -143.3 ps/nm by the addition to the CFBG of different lengths of single-mode fiber, without compromising shape invariance.

We propose a series of pulse generators based on Mach-Zehnder modulators biased at maximum transmission and overmodulated with a peak-to-peak voltage swing beyond the modulator's point of minimum transmission. In each driving cycle, the modulator output consists of two pairs of different pulses with perfectly timed zero crossings. The pulses are then passively equalized either by use of one-bit-delay interferometers or by a 1/2 Talbot dispersive line. The resulting pulse generators produce the formats 36% return-to-zero (RZ), 50% carrier-suppressed RZ (CSRZ), and 50% CSRZ with low alternate chirp alpha = plusmn0.2. All generators are driven by a single radio-frequency tone at one fourth of the desired bit rate.