2 GHz repetition-rate femtosecond blue sources by second harmonic generation in a resonantly enhanced cavity

Abstract

We report a 2 GHz repetition-rate, all-solid-state femtosecond blue source. Pumped by a 740 mW femtosecond Ti:sapphire laser with the same repetition rate, 150 mW femtosecond pulses at 409 nm can be efficiently generated from the external resonant cavity with a lithium triborate crystal.

?^(2) and ?^(3) harmonic generation at a critical power in inhomogeneous doubly resonant cavities

“…Second-harmonic generation in cavities with a single resonant mode at the pump frequency [10,14,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38] or the harmonic frequency [39] requires much higher power than a doubly resonant cavity, approaching one Watt [3,38] and/or requiring amplification within the cavity. (A closely related case is that of sum-frequency generation in a cavity resonant at the two frequencies being summed [40].)…”

“…In the following, we derive a semi-analytical description of harmonic generation using the framework of coupled-mode theory [1,2,3,5,9,10,14,31,37,47], and then check it via direct numerical simulation of the nonlinear Maxwell equations [7,48,49]. For maximum generality, we derive the coupled-mode equations using two complementary approaches.…”

Harmonic generation and wave mixing in nonlinear metamaterials and photonic crystals (Invited paper)

“…Another approach to increasing the SHG and THG efficiency exploits high strength of the fields localized in the resonant cavities [85–87]. The cavity is usually formed by the metallic mirrors and distributed Bragg reflectors (multilayered dielectric mirrors), which confine the field and thus facilitate the localized nonlinear interactions.…”

“…The latter phenomenon usually originates from the wave interference at the microscopic level, which leads to suppression of the propagating spatial harmonics and formation of the bandgaps. The nonlinear properties of multilayered PhC and MM have been investigated mainly in connection to improving the efficiency of frequency conversion and harmonic generation [24–109].…”

Degenerate four-wave mixing in triply resonant Kerr cavities

“…(In a χ (3) medium, there is a change in the refractive index proportional to the square of the electric field.) As in SHG, THG in doubly resonant cavities has been shown to support solutions with 100% conversion efficiency, even when taking into account nonlinear frequency shifting due to SPM and XPM, as well as interesting dynamical behavior such as multistability and limit cycles (self-pulsing) [1], with lower power requirements compared to singly resonant cavities or nonresonant structures [9,50,59,66,[70][71][72][73][74][75][76][77][78][79][80][81][82]. Limit cycles have been observed in a number of other nonlinear optical systems, including doubly resonant χ (2) cavities [46,83], bistable multimode Kerr cavities with time-delayed nonlinearities [84], nonresonant distributed feedback in Braggs gratings [19], and a number of nonlinear lasing devices [85].…”