AVS 58th Annual International Symposium and Exhibition
    Advanced Surface Engineering Division Wednesday Sessions
       Session SE+SS-WeM

Paper SE+SS-WeM5
Two-Color Time-Domain Thermoreflectance with an Optical Parametric Oscillator

Wednesday, November 2, 2011, 9:20 am, Room 104

Session: Surface Engineering for Thermal Management
Presenter: Jamie Gengler, Spectral Energies, LLC
Authors: J. Gengler, Spectral Energies, LLC
C. Muratore, Air Force Research Laboratory
S. Roy, Spectral Energies, LLC
J.R. Gord, Air Force Research Laboratory
Correspondent: Click to Email
Conventional single-color laser pump-probe methods for measuring thermal properties are limited by sample requirements that arise from considerations of surface roughness and compatible thermoreflectance transducers. Here we describe a new experimental arrangement for performing two-color time-domain thermoreflectance (TDTR). The technique is a variation of traditional pump-probe spectroscopy that is based on a femtosecond Ti:sapphire oscillator of fixed wavelength and an optical parametric oscillator (OPO), with the goal being to create an independently tunable probe wavelength. This method offers two advantages: 1) spectral filtering of diffusely scattered pump light (to prevent it from reaching the detector), and 2) generation of thermoreflectance signal from different metal thin films. The wavelength tunability of the system allows enhancement of TDTR signal generation for multiple thermoreflectance transducer materials. This wavelength-adjustable feature, in turn, facilitates direct measurement of the thermal transport properties of various thin films and substrates, which would be difficult with single-color femtosecond pump-probe systems. Demonstrated results include optimization of the probe wavelength for different metals, measurement of metal-graphite interfacial conductances on relatively rough samples, and two orders-of-magnitude calibration of thermal conductivity measurements using copper as a thermoreflectance transducer.