Brillouin scattering

About: Brillouin scattering is a research topic. Over the lifetime, 11426 publications have been published within this topic receiving 178306 citations.

Refractive index and elastic properties of single‐crystal corundum (α‐Al2O3) up to 2100 K

Abstract: We show that Brillouin scattering can be used to measure the elastic and optical properties of materials to very high temperatures. We have measured the elastic constants C11, C33, and C44 of single‐crystal sapphire in the temperature range 300–2100 K extending by 300 K the highest temperature previously attained with ultrasonic resonance techniques. The temperature dependence of the ordinary and extraordinary refractive indices no and ne in the same temperature range have been obtained for the first time. Although both no and ne are temperature dependent, the ratio no/ne is found to be almost temperature independent.

Thermal and mechanical properties of rare earth aluminate and low-silica aluminosilicate optical glasses

Abstract: Aluminate glasses containing 45–71.5 mol% alumina, 10–40 mol% rare earth oxide, and 0–30 mol% silica were synthesized from precursor oxides. The glass transition and crystallization temperatures were determined by differential scanning calorimetry; the structural and mechanical properties were investigated by Raman and Brillouin spectroscopy. The range of the supercooled liquid region varies from ∼40 °C to 200 °C, providing a useful working range for compositions with 5–30 mol% silica. Raman scattering showed the presence of isolated SiO 4 species that strengthen the network-forming structure, enhance glass formation, and stabilize the glass even when they are present at fairly low concentrations. Sound velocities were measured by Brillouin scattering. From these and other values, various elastic moduli were calculated. The moduli increased with both aluminum and rare earth content, as did the hardness of the glasses. Young’s modulus was in the range 118–169 GPa, 60–130% larger than that for pure silica glass.

High-sensitivity and high-specificity biomechanical imaging by stimulated Brillouin scattering microscopy

Abstract: Label-free, non-contact imaging with mechanical contrast and optical sectioning is a substantial challenge in microscopy. Spontaneous Brillouin scattering microscopy meets this challenge, but encounters a trade-off between acquisition speed and the specificity for biomechanical constituents with overlapping Brillouin bands. Stimulated Brillouin scattering microscopy overcomes this trade-off and enables the cross-sectional imaging of live Caenorhabditis elegans at the organ and subcellular levels, with both elasticity and viscosity contrasts at high specificity and with practical recording times.

Ultra-narrow linewidth Brillouin laser with nanokelvin temperature self-referencing

Abstract: Ultrastable lasers serve as the backbone for some of the most advanced scientific experiments today and enable the ability to perform atomic spectroscopy and laser interferometry at the highest levels of precision possible. With the recent and increasing interest in applying these systems outside of the laboratory, it remains an open question as to how to realize a laser source that can reach the extraordinary levels of narrow linewidth required and still remain sufficiently compact and portable for field use. Critical to the development of this ideal laser source is the necessity for the laser to be insensitive to both short- and long-term fluctuations in temperature, which ultimately broaden the laser linewidth and cause drift in the laser’s center frequency. We show here that the use of a large mode-volume optical resonator with 2 m of optical fiber, which acts to suppress the resonator’s fast thermal fluctuations, together with stimulated Brillouin scattering optical nonlinearity presents a powerful combination that enables lasing with an ultra-narrow linewidth of 20 Hz. To address the laser’s long-term temperature drift, we apply two orthogonal polarizations of the narrow Brillouin line as a metrological tool that precisely senses a minute change in the resonator’s temperature at the level of 85 nK. The precision afforded by this temperature measurement enables new possibilities for the stabilization of resonators against environmental perturbation.

Threshold for stimulated Brillouin scattering in optical fiber.

Abstract: We show that in optical fiber the threshold exponential gain, Gth, for stimulated Brillouin scattering initiated by spontaneous Brillouin scattering is functionally and strongly dependent on the material, length and numerical aperture of the fiber and the pump wavelength. For silica fiber we show that the value of Gth at λ≅1 µm ranges from as low as ~5 in long fiber (≥ few kms) to ~10–12 in fibers of ~100 m length and ~20–23 for very short fibers (<10 cm).