Radiation Pressure Induced Four-wave Mixing Process In Membrane Cavity Optomechanical Systems

The interaction between light field and matter is an important area in quantum optics.Although began late,the cavity optomechanics become a hotspot in research of quantum optics for its unrivalled characteristic and bright future of applications.Cavity optomechanics,which studies the interaction between the optical field in the cavity and the mesoscopic mechanical resonators,has a broad fields involved not only in quantum optics,but also micro/nano photonics,materials science and mechanical science.As a developing cross-science,the developing of cavity optomechanics will definitely promote the independent and development of quantum acoustics.In the terms of the research of basic science,cavity optomechanics provide a favorable platform for the study of quantum phenomena in macroscopic objects and quantum-classical boundary.On the other hand,cavity optomechanics can be widely applied in high-precision measurements such as the detection of weak force tiny mass and displacement and even the gravitational waves.Moreover,cavity optomechanics provides useful tools for quantum communication processing for it is not only good carriers for information storage,but also can act as the media of the conversion between microwave and optical lightThis dissertation is devoted to the theoretical and experimental study on membrane cavity optomechanics,including the optomechanical coupling,the preparation of high mechanical quality membrane resonator,the cooling of the mechanical motion and radiation pressure induced four-wave mixing in such system.The main content is divided into the following four parts:1,By setting a high stress SiN membrane inside a high finesse FP cavity,we built a membrane cavity optomechanical system.We study the influence of the dispersion and optical dissipation of the system induced by the real and imaginary part of the refractive index of the membrane in the optical cavity.We further propose the motivation of the optical multimode and strong nonlinear coupling process which induced by the misalignment of the surface of the membrane and the wavefront of the cavity field.2,The elements that dominate the mechanical dissipation of the membrane resonator,including the internal banding loss which induced by the intermolecular friction and the external loss caused by clamping,which also called phonon tunneling loss,are analyzed.For our experiment system,the clamping loss is the most important limit factor of the quality factor of the resonator.We propose two schemes to suppress the clamping loss and enhance the quality factor.The first regime is based on the fiber strings which isolated the membrane frame from the environment for it has giant mismatch of acoustic impedance and enhanced the reflectivity of acoustic waves.The quality factor of the fundamental mode of the membrane is more than a million in this scheme.We further make a low frequency resonator on the membrane frame chip which act as an acoustic low pass filter and suppress the phonon tunneling loss.This regime can enhance the quality factor of several modes at the same time.3,cooling the mechanical motion down to the quantum ground state is the requirement for quantum interaction between the light fields and the mechanical resonators.This thesis propose the quantum limit of sideband cooling and the condition of strong coupling via the analyze of quantum theory of sideband cooling.On the other hand,the feedback cooling has better performance in regime of unresolved sideband where the quantum limit of sideband cooling is larger than one due to the two-mode squeezing interaction,and the quantum limit of feedback cooling is depended on the efficiency of position detection.We propose a scheme that apply the feedback process in membrane optomechanical system where the efficiency of the position detection is much higher than other systems and the motion of the membrane resonator in unresolved sideband regime can be cooled to the quantum ground state via feedback cooling in theory.4,Four-wave mixing(FWM)has been achieved in various media including atomic vapors,nonlinear crystals,and optical fibers,and has found numerous applications in the fields of nonlinear optics and quantum optics.Unfortunately,due to the determinate natural energy level of atom and nonlinear media,only few wavelength of optical field which couple the energy level of these media can be operated in these systems.On the other hand,benefited to the manmade energy level depend on the optical cavity and mechanical resonator,the cavity optomechanical system can be operated in a broad wavelength range,even in the microwave band.In the last decade,radiation-pressure-induced FWM in a cavity optomechanical system has been investigated in a resolved sideband regime theoretically.In this thesis we propose a regime to achieve FWM process in unresolved side range.A tunable multimode FWM process in an unresolved sideband membrane optomechanical system has been achieved.The FWM mechanism enables remarkable amplification of a weak signal field with ultralow added noise,and accompanied by the generation of an FWM field when only microwatt-level pump field is applied.The magnification of the signal beam and the frequency response of the process can be dynamically tuned by varying the detuning and intensity of pump beam.A more than 40 dB intensity magnification with less than 9Hz full width at half maximum is realized by our device.This issue,which based the interaction between the cavity field and mechanical resonator,has proposed a large possibility to realize FWM process in any range of wavelength of optical field,even in microwave range,and offer an ultranarrow linewidth of an optical system in a compact device.