Čerenkov difference frequency generation in a two-dimensional nonlinear photonic crystal

Abstract

We present experimental realization of Cerenkov difference frequency generation (CDFG) in a 2-dimentional rectangular periodically poled LiTaO 3. The backward reciprocal vector of the nonlinear photonic crystal accelerates the phase velocity of the nonlinear polarization wave so as to exceed the phase speed limit of achieving Cerenkov down-conversions in this normal dispersion medium. Some characteristics of CDFG, such as radiation angles, pumping power, and pulse temporal overlapping dependences were discussed. The experimental results matched well with theoretical predictions. V

Enhanced nonlinear Cherenkov radiation on the crystal boundary

“…This could be explained by two main reasons: First, the new enhanced elements of susceptibility tensor in domain wall resulting from lattice distortion or internal local electrical field by poling process [8]; and second, arbitrary reciprocal vectors provided by the antiparallel domains across the domain wall [10], which could compensate for the phase mismatch in the nonlinear optical process. Besides Cherenkov SH generation, many other Cherenkov-type nonlinear processes have been found, including sum frequency generation [11,12], third and higher order harmonic generation [13,14], difference frequency generation [15], and so on. Since NCR is a noncollinear auto-phase-matched frequency conversion process and is quite sensitive to the ferroelectric domain wall, it has been utilized as an effective tool for nondestructive diagnostics, microscopy [16] and ultrashort pulse characterization [12].…”

Nonlinear Cherenkov radiation at the interface of two different nonlinear media

“…Previous studies demonstrated that, under anomalous-like dispersion conditions, NCR can also be generated by modulating the phase velocity of the polarization wave [2]. NCR has been thoroughly researched in different nonlinear processes, such as second [3] and cascaded high-order harmonic generation [4][5][6], sum-frequency generation [7], and difference-frequency generation [8]. Such studies suggest potential applications to efficient frequency conversion [9], terahertz wave generation [10], ultrashort pulse-sharping [11], non-destructive domain-wall detection and imaging [12,13], and so on.…”

Sum-frequency nonlinear Cherenkov radiation generated on the boundary of bulk medium crystal

“…Due to the tolerant requirement for auto-phasematching, NCR has attracted lots of attention in the past few years. Many different type of NCR phenomenon have been observed, for example, Cherenkov type sum-frequency generation [3,4], third and higher order harmonic generation [5,6], difference frequency generation [7], and so on. Since NCR provides a tolerant phase-matching approach for frequency conversion, it has a great application prospect for nondestructive diagnostics, microscopy [8] and ultra-short pulse characterization [3].…”