kHz stimulated Brillouin spectroscopy

Abstract

We have developed a high precision stimulated Brillouin spectrometer. Since this spectrometer is based on the stimulated light scattering, Brillouin measurements are possible without any signal reduction even at extremely low temperatures. The use of stable lasers for the pump and probe waves and a real-time frequency-monitor gives a high frequency resolution reaching 20 kHz, which is, to the best of authors knowledge, the highest resolution so far reported for Brillouin spectrometers. The frequency-monitor has been achieved through the measurement of the beat frequency between the two lasers by using a microwave frequency counter. With this spectrometer, we have succeeded to measure Brillouin spectra in single crystals of TeO2 from room temperature to liquid helium temperature. Furthermore, in a sample with [110] surfaces, we have observed a spectral splitting due to the multireflection of phonons at crystal surfaces.

Optical Control of Bulk Phonon Modes in Crystalline Solids

“…[17] Although electromechanical techniques provide a very effective method for studying phonon physics at cryogenic temperature, [5b] they are not suitable for non-piezoelectric crystals. In 2006, stimulated Brillouin spectroscopy of tellurium dioxide (TeO 2 ) crystals at cryogenic temperatures by Ohno et al [18] revealed new features due to the reflection of traveling acoustic waves at the crystal surfaces. These measurements confirm that Brillouin scattering can be used to both generate and detect standing-wave phonon modes within crystals at cryogenic temperatures.…”

“…Stimulated Brillouin spectroscopy of TeO 2 crystals is confirmed to be used to both generate and detect phonon modes within crystals at cryogenic temperatures. [18]…”

“…[30] Since the linewidth of Brillouin spectra in crystals is usually about a few MHz at cryogenic temperatures, it is difficult to resolve due to the limitation of the Fabry-Pérot interferometer. Until 2006, Ohno et al [18] developed stimulated Brillouin spectrometer. Based on phase-matched Brillouin interactions, they achieve the highest frequency resolution which is lower than 20 kHz.…”

Frequency-modulated stimulated Brillouin spectroscopy in high-refractive-index glasses

“…Fortunately, we have recently developed frequencymodulated (FM) stimulated Brillouin spectroscopy employing Nd:YAG lasers with the lasing wavelength of 1.06 lm [6,7]. This spectrometer has the spectral resolution of 20 kHz in the case of 30 cm focal length lense and is capable of detecting separately the imaginary and real parts of Brillouin spectrum.…”

Non-Gaussian Mechanical Motion via Single and Multiphonon Subtraction from a Thermal State

“…For this experiment, we would like to highlight four key pathways for improvement: (i) operation at cryogenic temperature to reduce the material contributions to the mechanical decay rate [1][2][3]50], (ii) increasing the drive strength and utilizing the optomechanical strong coupling available in Brillouin optomechanical systems [51], (iii) further tapered fiber and microresonator optimization to enable better optical coupling with respect to the intrinsic cavity losses, and (iv) utilizing a Stokes interaction for mechanical state preparation, followed by an anti-Stokes interaction for the readout, to provide a route to make the readout more independent and remove the beam splitter for the single-photon detection to improve the efficiency. Implementing these four improvements provides a promising path to achieving an overall anti-Stokes readout measurement efficiency exceeding 50%.…”