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The resonance frequency of an optical whispering gallery mode (WGM) microcavity is extremely important in its various applications. Many efforts have been made to fine tune this parameter. Here, we report the design and implementation of a function resonance tuner of an optical microcavity with resolution about 650 kHz (7 pm @ 1450 nm band), 20% of the optical WGM linewidth. A piezoelectric nano-positioner is used to mechanically compress the microsphere in its axial direction. The ultrafine frequency tuning is achieved benefitting from the much less changes in the axial direction than equatorial semiaxes of the microsphere and the sub-nanometer resolution of the nano-positioner. The tuning of the resonance can be made to an arbitrary function, dynamically, with near perfect accuracy. We have demonstrated the periodically tuning of resonance in the sine and sigmoid function respectively, both with over 99% fitting accuracy. This work expands the application of microresonators greatly, especially microspheres with ultrahigh quality factor, in multi-mode coupling system or time-floquet system.
We report on two ultrastable lasers each stabilized to independent silicon Fabry-Perot cavities operated at 124 K. The fractional frequency instability of each laser is completely determined by the fundamental thermal Brownian noise of the mirror coa
Broadband precision spectroscopy is indispensable for providing high fidelity molecular parameters for spectroscopic databases. We have recently shown that mechanical Fourier transform spectrometers based on optical frequency combs can measure broadb
We demonstrate two fully and tightly phase locked 750 MHz ytterbium (Yb) fiber frequency combs that are independently stabilized to a continuous wave (CW) laser with <1 rad RMS phase error. A bulk EOM and a single stack PZT are separately utilized as
We demonstrate a neutron tomography technique with sub-micrometer spatial resolution. Our method consists of measuring neutron diffraction spectra using a double crystal diffractometer as a function of sample rotation and then using a phase retrieval
We present a method for 3D sub-nanometer displacement measurement using a set of differential optical shadow sensor. It is based on using pairs of collimated beams on opposite sides of an object that are partially blocked by it. Applied to a sphere,