All-solid-state VUV frequency comb at 160 nm using multi-harmonic generation in a non-linear femtosecond enhancement cavity

Abstract

We report on the realization of a solid-state-based vacuum ultraviolet frequency comb, using multi-harmonic generation in an external enhancement cavity. Optical conversions in such arrangements were so-far reported only using gaseous media. We present a theory that allows selecting the most suited solid generation medium for specific target harmonics by adapting the bandgap of the material. Consequently, we experimentally use a thin AlN film grown on a sapphire substrate to realize a compact frequency comb multi-harmonic source in the DUV/VUV spectral range. Extending our earlier VUV source [Opt. Exp. 26, 21900 (2018)] with the enhancement cavity, a sub-Watt level Ti:sapphire femtosecond frequency comb is enhanced to 24 W stored average power, its 3rd, 5th and 7th harmonics are generated, and the target harmonic power at 160 nm increased by two orders of magnitude. The emerging non-linear effects in the solid medium together with suitable intra-cavity dispersion management support optimal enhancement and stable locking. To demonstrate the spectroscopic ability of the realized frequency comb, we report on the beat measurement between the 3rd harmonic beam and a 266 nm CW laser reaching about 1 MHz accuracy.

References in corpus (10)

• Direct Frequency Comb Spectroscopy in the Extreme Ultraviolet
• VUV frequency combs from below-threshold harmonics
• Nuclear clocks based on resonant excitation of gamma-transitions
• Phase-matched extreme-ultraviolet frequency-comb generation
• Extreme Nonlinear Optics in a Femtosecond Enhancement Cavity
• XUV Frequency Combs via Femtosecond Enhancement Cavities
• XUV frequency comb metrology on the ground state of helium
• Towards a 229Th-based nuclear clock
• Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions
• Non-planar femtosecond enhancement cavity for VUV frequency comb applications

Cited by in corpus (5)

• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• Concepts for direct frequency-comb spectroscopy of ${}^{229\text{m}}$Th and an internal-conversion-based solid-state nuclear clock
• Tunable VUV Frequency Comb for ${}^{229m}$Th Nuclear Spectroscopy
• A low repetition rate optical frequency comb
• Coherent suppression and dephasing-induced reentrance of high harmonics in gapped Dirac materials