Doctor of Philosophy, Stanford University, EE-PMN (2016)
Doctor of Philosophy, Stanford University, ME-PHD (2016)
Master of Science, Stanford University, ME-MS (2012)
Bachelor of Engineering, Zhejiang University, Energy Engineering (2010)
- On-Chip Laser-Power Delivery System for Dielectric Laser Accelerators PHYSICAL REVIEW APPLIED 2018; 9 (5)
Differential optical shadow sensor for sub-nanometer displacement measurement and its application to drag-free satellites
2017; 25 (21): 25201–11
We present a method for 3D sub-nanometer displacement measurement using a set of differential optical shadow sensors. 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, our 3-axis sensor module consists of 8 parallel beam-detector sets for redundancy. The sphere blocks half of each beam's power in the nominal centered position, and any displacement can be measured by the differential optical power changes amongst the pairs of detectors. We have experimentally demonstrated a displacement sensitivity of 0.87nm/Hz at 1 Hz and 0.39nm/Hz at 10 Hz. We describe the application of the module to the inertial sensor of a drag-free satellite, which can potentially be used for navigation, geodesy and fundamental science experiments as well as ground based applications.
View details for DOI 10.1364/OE.25.025201
View details for Web of Science ID 000413103300033
View details for PubMedID 29041190
Measuring finesse and gas absorption with Lorentzian recovery spectroscopy
2017; 25 (7): 7645-7655
In this paper we present a method for obtaining accurate finesse by recovering the Lorentzian profile of cavity resonances with a laser continuously locked to the cavity and apply it to weak gas absorption measurements. The technique was implemented on our noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) experimental setup. The measurement is performed in the cavity-locked regime, leading to high repeatability and easy automation. The technique involves locking the carrier to a fundamental mode of the cavity and sweeping a second set of sidebands across adjacent cavity modes. The Lorentzian line shape can be reconstructed through a measurement of the transmitted optical power of the auxiliary sidebands. The cavity finesse and gas absorption can then be extracted from these power measurements. The accuracy of our measurements was verified by comparing our results to those obtained with the cavity ring down technique. We demonstrate the use of the technique in spectroscopy by measuring the absorption coefficient of the R(14) line of 12C16O that has been well characterized by others. The gas absorption results obtained were consistent with other experimental measurements and theoretical calculations.
View details for DOI 10.1364/OE.25.007645
View details for Web of Science ID 000398536000044
View details for PubMedID 28380884
Pico-Kelvin thermometry and temperature stabilization using a resonant optical cavity
2017; 25 (4): 3578-3593
Ultra-high sensitivity temperature sensing and stable thermal control are crucial for many science experiments testing fundamental theories to high precision. Here we report the first pico-kevin scale thermometer operating at room temperature with an exceptionally low theoretical noise figure of ~70pK/Hz at 1 Hz and a high dynamic range of ~500 K. We have experimentally demonstrated a temperature sensitivity of <3.8nK/Hz at 1 Hz near room temperature, which is an order of magnitude improvement over the state of the art. We have also demonstrated an ultra-high stability thermal control system using this thermometer, achieving 3.7 nK stability at 1 s and ∼ 120 pK at 104 s, which is 10-100 times more stable than the state of the art. With some upgrades to this proof-of-principle device, we can expect it to be used for very high resolution tests of special relativity and in critical point phenomena.
View details for DOI 10.1364/OE.25.003578
View details for Web of Science ID 000397317400065
View details for PubMedID 28241571
Phonon Dominated Heat Conduction Normal to Mo/Si Multilayers with Period below 10 nm
2012; 12 (6): 3121-3126
Thermal conduction in periodic multilayer composites can be strongly influenced by nonequilibrium electron-phonon scattering for periods shorter than the relevant free paths. Here we argue that two additional mechanisms-quasiballistic phonon transport normal to the metal film and inelastic electron-interface scattering-can also impact conduction in metal/dielectric multilayers with a period below 10 nm. Measurements use the 3ω method with six different bridge widths down to 50 nm to extract the in- and cross-plane effective conductivities of Mo/Si (2.8 nm/4.1 nm) multilayers, yielding 15.4 and 1.2 W/mK, respectively. The cross-plane thermal resistance is lower than can be predicted considering volume and interface scattering but is consistent with a new model built around a film-normal length scale for phonon-electron energy conversion in the metal. We introduce a criterion for the transition from electron to phonon dominated heat conduction in metal films bounded by dielectrics.
View details for DOI 10.1021/nl300996r
View details for Web of Science ID 000305106400078
View details for PubMedID 22563928
ELECTRON-PHONON COUPLED TWO-DIMENSIONAL HEAT TRANSFER IN NANOSCALE METAL/DIELECTRIC MULTILAYERS
ASME Summer Heat Transfer Conference (SHTC)
AMER SOC MECHANICAL ENGINEERS. 2012: 579–587
View details for Web of Science ID 000324956600068