Research Of Light-matter Interaction Based On The Strong Coupling Micro-cavity

In this paper,we have demonstrated that the electric field（E）of fundamental frequency（FW）is enhanced and high efficient second harmonic generation（SHG）from the hyper-Rayleigh scattering（HRS）is obtained in the hybrid strong coupling micro-cavity waveguide（HSCMW）.In this experiment,we start with a description on the physical picture of SHG process by theoretical analysis.When FW is coupled into the capillary,two scatterings of the particle occur simultaneously:one is linear Rayleigh scattering（RS）with same frequency as FW,and the other is second order nonlinear HRS with double frequency.The intensity of SHG from every polarized particle radiating is incoherent superposition along capillary,and the strong second harmonic wave beam can be detected from micro-cavity.For understanding the physics behind the analysis mentioned above,we have calculated the intensity of SHG.Under the electric dipole approximation,the action of a single scattered particle is described by hyperpolarization.Further numerical calculation shows that the intensity of light is proportional to the square of E,and the intensity of second harmonic wave is proportional to the fourth power of fundamental frequency wave E.Therefore,efficient SHG can be realized from HRS by our HSCMW which has an enhancement on E.The continuous wave（cw）light was coupled into the micro-cavity with high coupling efficiency more than 99%by free space coupling technology.The ultrahigh-order modes（UOMs）was excited and the E of FW was enhanced due to standing wave local oscillation.In the cavity of HSCMW,the E was enhanced for the second time.HRS was occurred by lithium niobite（LN）powder through the enhanced FW in microcavity,resulting in direct observation of second harmonic beam in the capillary port.The combination of HRS and HSCMW will provide a new way to break through phase-matching limitations,with relatively high conversion efficiency measured to be 0.032%/W in our experiment.Meanwhile,the relationship between the intensity of SHG and the concentration of LN solution,and the incident light intensity was studied and analyzed.This work suggests a progress on frequency conversion and is also applicable to other nonlinear processes in waveguide.Compared with the traditional SHG,our SHG combining HRS with HSCMW simplifies the machining process and complex structure greatly.It also provides a potential method for nonlinear frequency conversion research with high conversion efficiency.For further research,we will consider chemical surface modification on particles which can prevent particles from clustering to obtain higher conversion efficiency.Confining light in a micro-cavity is important in both nonlinear optics and guide wave optics.The symmetrical metal-cladding optical waveguide（SMCOW）with high quality factor Q has been researched which possesses many superior performances,such as high sensitivity,and high power density,due to the excited ultrahigh-order guided modes（UOGMs）standing wave field oscillating between the top and bottom layer at a very small incident angle.In conclusion,we have experimentally detected and theoretically simulated the relationship between Q and thickness of waveguide layer as well as incident angle,and high Q～1.1×10⁵ is achieved through SMCOW with simple processing technique.The relationship between Q and thickness of waveguide layer is proportional,and the relationship between Q and incident angle is inverse.Also,we have deduced the equation of an important parameter,the half width Wθof the Attenuated Total Reflectance（ATR）,which is dependent on the imaginary part of propagation constant Im（β^L）and incident angleθ_ATR.In this paper,we have studied the light-matter interaction in HSCMW by generation of high efficient SHG through HRS,and by experiment and calculation of quality factor Q in SMCOW.