title: Evanescent straight tapered-fiber coupling of ultra-high Q optomechanical micro-resonators in a low-vibration helium-4 exchange-gas cryostat.
abstract: We developed an apparatus to couple a 50-μm diameter whispering-gallery silica microtoroidal resonator in a helium-4 cryostat using a straight optical tapered-fiber at 1550 nm wavelength. On a top-loading probe specifically adapted for increased mechanical stability, we use a specifically-developed "cryotaper" to optically probe the cavity, allowing thus to record the calibrated mechanical spectrum of the optomechanical system at low temperatures. We then demonstrate excellent thermalization of a 63-MHz mechanical mode of a toroidal resonator down to the cryostat's base temperature of 1.65 K, thereby proving the viability of the cryogenic refrigeration via heat conduction through static low-pressure exchange gas. In the context of optomechanics, we therefore provide a versatile and powerful tool with state-of-the-art performances in optical coupling efficiency, mechanical stability, and cryogenic cooling.
authors: École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors: R
authors: R
authors: Rivière
authors: O
authors: O
authors: Arcizet
authors: A
authors: A
authors: Schliesser
authors: T J
authors: TJ
authors: Kippenberg