Continuous-Wave Molecular Modulation Using a High-Finesse Cavity

Abstract

Abstract:We demonstrate an optical modulator at a frequency of 90 THz that has the capability to modulate any laser beam in the optical region of the spectrum. The modulator is constructed by placing deuterium molecules inside a high-finesse cavity and driving a vibrational transition with two continuous-wave laser beams. The two beams, the pump and the Stokes, are resonant with the cavity. The high intra-cavity intensities that build up drive the molecules to a coherent state. This molecular coherence can then be used to modulate an independent laser beam, to produce frequency up-shifted and down-shifted sidebands. The beam to be modulated is not resonant with the cavity and thus the sidebands are produced in a single pass.

Chiral Rotational Spectroscopy

“…Fine tuning the polarization properties of the light in the active region enables the refinement of magic transitions, to help overcome stringent requirements on the intensity of the light and thus obtain a clean chiral rotational spectrum. The optical cavity might be of the skew-square ring variety, comprised of low-loss, ultra-high-reflectivity, lowanisotropy mirrors [111,112] while the light might originate from an external cavity diode laser, the output of which is fiber amplified and mode matched into the ring with stability actively enforced [113,114]. We envisage the light to be continuous wave here, with a central intensity of at least 10 11 kg s −3 (10 7 W cm −2 ).…”

“…9. Note in particular the implied circulating light power of 1.00 × 10 5 kg m 2 s −3 in the optical cavity, which should be achievable using an input light power of 1.00 × 10 2 kg m 2 s −3 or less, assuming a transmittance of 2.50 × 10 −4 or less for each light mirror and neglecting loss [112][113][114]132]. Significantly higher circulating light powers than this have certainly been demonstrated, also in the context of molecular alignment [133].…”

Chiral rotational spectroscopy

“…Fine-tuning the polarisation properties of the light in the active region enables the refinement of magic transitions, to help overcome stringent requirements on the intensity of the light and thus obtain a clean chiral rotational spectrum. The optical cavity might be of the skew-square ring variety, comprised of low-loss, ultra-high-reflectivity, low-anisotropy mirrors [111,112] whilst the light might originate from an external cavity diode laser, the output of which is fibre amplified and mode matched into the ring with stability actively enforced [113,114]. We envisage the light to be continuous wave here, with a central intensity of at least 10 11 kg.s −3 (10 7 W.cm −2 ).…”

“…(iv) An evacuated chamber encompasses the key components described above to eliminate atmospheric interference with the molecular pulses and facilitate the removal of molecules between measurements. The absence of air, dust and other such influences should assist moreover in maintaining the stability of the optical cavity [114].…”

Multicolored Femtosecond Pulse Synthesis Using Coherent Raman Sidebands in a Reflection Scheme

“…Meanwhile, the molecular modulation method has been extended to the continuous-wave (CW) domain. For example, Yavuz's group has studied CW-stimulated Raman scattering (SRS) inside a high-finesse cavity and demonstrated a continuous-wave optical modulator at 90 THz [14]. Generation of a phase-locked Raman frequency comb has been demonstrated recently in a simple setup consisting of a microchip laser as pump source and two hydrogen-filled hollow-core photonic crystal fibers [15].…”