Albert Schliesser

High-sensitivity monitoring of micromechanical vibration using optical whispering gallery mode resonators

The inherent coupling of optical and mechanical modes in high finesse optical microresonators provides a natural, highly sensitive transduction mechanism for micromechanical vibration. Using homodyne and polarization spectroscopy techniques, we achieve shot-noise limited displacement sensitivities of . In an unprecedented manner, this enables the detection and study of a variety of mechanical modes, which are identified as radial breathing, flexural and torsional modes using three-dimensional finite element modeling. Furthermore, a broadband equivalent displacement noise is measured and found to agree well with models for thermorefractive noise in silica dielectric cavities. Implications for ground-state cooling, displacement sensing and Kerr squeezing are discussed.

Cavity quantum optomechanics: Coupling light and micromechanical oscillators

Cavity optomechanics1 is a new research field that has seen spectacular advances in recent years. Optomechanics combines advances in nano- and electromechanical systems with radiation pressure enabled control. The radiation pressure backaction enables to readout mechanical motion of micro- and nanoscale mechanical oscillators with an imprecision at the standard quantum limit, enables to amplify2 mechanical motion - enabling coherent mechanical oscillators. Likewise the cooling3,4 of mechanical oscillators has enabled to access the quantum regime of optomechanical systems. Likewise mechanical degrees of freedom provide new ways to control the propagation of light via the phenomenon of optomechanically induced transparency5, which can e.g. enable switching, slowing or advancing of electromagnetic pulses6. Cavity optomechanical systems also have reached the quantum regime of mechanical oscillators, which has been long anticipated. As one example of the possible range of optomechanical phenomena, we review an optomechanical microresonator in which optical and mechanical degrees of freedom exchange energy at a rate exceeding the relevant decoherence rates in the system, enabling quantum control of a mechanical oscillator with light. Such quantum coherent coupling provided a quantum coherent link7 between engineered microscale oscillators and the light field.

Cooling of a Micro-Mechanical Oscillator Using Radiation Pressure Induced Dynamical Back-Action

We demonstrate how dynamical backaction of radiation pressure can be exploited for passive laser-cooling of high-frequency (>50 MHz) mechanical oscillation modes of ultra-high-finesse optical microcavities from room temperature to below 10 K.

Observation of optomechanical coupling in crystalline whispering gallery mode resonators

The coupling of optical and mechanical degrees of freedom gives rise to a number of long-anticipated phenomena, such as cooling or amplification of mechanical motion. Particularly promising candidates for the emerging field of cavity optomechanics are microresonators such as silica microtoroids [1]. However, these structures suffer from strong mechanical dissipation at cryogenic temperatures, caused by two-level fluctuators in the amorphous material. It is therefore of interest to use a crystalline material such as quartz or CaF2, which supports mechanical Q factors ≫108 at low temperatures [2]. While crystalline whispering gallery mode resonators, as pioneered by Maleki and co-workers have attained record Q factors exceeding 1011 in the optical domain [3], their optomechanical properties have so far neither been observed nor studied.

Controlling Light Propagation via Radiation Pressure and Optomechanical Coupling

We experimentally demonstrate for the first time the possibility of controlling the propagation properties of a light pulse using cavity assisted radiation pressure coupling to mechanical modes. Both pulse delay and advancement are experimentally demonstrated.

Optical Frequency Comb Generation from a Monolithic Micro-Resonator via the Kerr Nonlinearity

It is shown that the cascaded optical sidebands generated via optical parametric oscillations in a monolithic microcavity are equidistant down to a resolution bandwidth limited level of 2 kHz.

Cooling of a Micro-Mechanical Oscillator Using Radiation-Pressure Induced Dynamical Backaction

We demonstrate how dynamical backaction of radiation pressure can be exploited for passive laser-cooling of high-frequency (> 40 MHz) mechanical oscillation modes of ultra-high-finesse optical microcavities from room temperature to 8 K.

Generation of an Optical Frequency Comb from a Monolithic Micro-Resonator via the Kerr Nonlinearity

It is shown that the cascaded optical sidebands generated via optical parametric oscillations in a monolithic microcavity are equidistant and lead to the generation of femtosecond pulses in time domain.