Nonlinear microfiber loop resonators for resonantly enhanced third harmonic generation

Abstract

We model and demonstrate resonantly enhanced third harmonic generation in microfiber loop resonators, in which the large pump field intensity is exploited to improve the conversion on resonance. Silica microfibers were fabricated with waist diameters near 0.76 μm to ensure intermodal phase matching. When pumped with λ=1.55 μm 4 ns pulses at 100 W peak power, the conversion efficiency is 3×10(-6) over an estimated interaction length of ∼1 mm near the waist. The resonator is then formed by manually translating and twisting the microfiber ends to produce loop diameters down to 6 mm and resonant enhancements up to 7.7 dB for the same pump parameters.

[INVITED] Optical microfibre devices

“…OMs usually provide efficient modal confinement to sizes smaller than the wavelength, resulting in enhanced nonlinearity and in phenomena like supercontinuum generation [52][53][54][55][56][57], second-and third-harmonic generation [58][59][60][61][62][63][64][65][66][67][68][69][70][71], slow and fast light [72] and bistability [72][73][74] being readily observed. Supercontinuum was generated in silica [6], bismuth-silicate [12] and chalcogenide [75] glasses.…”

Silica nanowires for UV light generation and sensing

“…In addition to the strong modal confinement and high nonlinearity (two orders of magnitude larger than a conventional telecom fibre), SNs display negligible input/output coupling losses, a tailorable dispersion profile and an extraordinarily high refractive index difference with the surrounding medium, which in the case of air produces numerical apertures in excess of unity. Our recent work focused on SN nonlinearities in relation to supercontinuum (SC), third harmonic (THG) and second harmonic generation (SHG) allowed for the demonstration of light generation at short wavelengths [3][4][5]. Particularly important has been the use of resonators to increase the effective SN nonlinearities, as these at the resonant wavelength recirculate the pump to produce enhancements at the second-or third-harmonic wavelengths [4,5].…”

“…Our recent work focused on SN nonlinearities in relation to supercontinuum (SC), third harmonic (THG) and second harmonic generation (SHG) allowed for the demonstration of light generation at short wavelengths [3][4][5]. Particularly important has been the use of resonators to increase the effective SN nonlinearities, as these at the resonant wavelength recirculate the pump to produce enhancements at the second-or third-harmonic wavelengths [4,5].…”

Chalcogenide microresonators tailored to distinct morphologies by the shaping of glasses on silica tapers

“…Recently, microfiber loop resonators, for which the problem of optical coupling with a resonator is naturally solved, are drawing significant interest [22], and various applications have been demonstrated [23]. The production of a silica microfiber loop resonator can be easily achieved by creating a self-touching loop pushing the fiber ends together after silica fiber tapering.…”