The Advanced Optical Spectroscopy & Microscopy Facility combines a broad range of optical instruments suitable for studies of optical properties of hard, soft or biological materials using ultrafast and nonlinear spectroscopy, and single-molecule optical and confocal methods.
Contact: Matthew Sfeir
Our facility houses a state-of-the-art high power kilohertz femtosecond regenerative amplifier combined with an optical parametric amplifier that allows generation of sub 100 femtosecond pulses in the ultraviolet, visible, and infrared regions of the spectrum. This system is coupled to a series of user-friendly time-resolved and nonlinear optical techniques, providing Users with a broad suit of tools for characterizing the photophysical properties of their materials, including:
The CFN houses a broadband transient absorption spectrometer with approximately 100 fs time resolution in a time window of 0 - 3 ns. In this technique, the samples are optically "pumped" using a tunable (240 - 2600 nm) femtosecond laser pulse and "probed" for changes in transmission using a "white-light" laser generated supercontinuum. The system can be configured to record spectral transients in one of three operating modes: 350 - 700 nm, 450 - 820 nm, or 800 - 1600 nm. Sample holders for cuvettes and thin films are available.
In addition, the broadband transient absorption spectrometer can be configured to measure long-lived electronic and chemical species with sub-ns time resolution in a time window of 0 - 50 microseconds. In this configuration, spectral transients can be recorded in one of two operating modes: 370 - 900 nm or 800 - 1700 nm. Sample holders for cuvettes and thin films are available. This is an optically gated technique using a femtosecond excitation pulse and a longer (~ 500 ps) white-light laser probe pulse.
This spectrometer is able to measure ultrafast emission processes in the visible and NIR (400 - 1600 nm) with a time resolution of ~ 100 fs in a time window of 0 - 3 ns. In the upconversion method, the emitted photons are mixed with an optical gate pulse in a nonlinear crystal optimized for sum frequency generation. We detect the intensity of the higher energy upconverted photons as a function of time delay between the excitation pulse and the gate pulse to map out the kinetics. Alternatively, spectral emission transients can be recorded at a fixed delay time. For longer kinetic processes, the spectrometer can also be operated in time-correlated single photon counting mode (TCSPC) in which the emitted photons are directly detected. The use of fast electronics allows for a time resolution of 100 ps over a range of 0 – 1 ms.
We have implemented this technique for measuring multi-photon absorption coefficients and nonlinear refractive indices of novel photonic materials. In this experiment, a thin solid or liquid sample is translated through the focus of high pulse energy NIR light (700 – 1200 nm). The normalized transmission is detected as a function of position along the light focus and used to derive the nonlinear optical coefficients.
Contact: Mircea Cotlet
Open frame scanning-stage confocal fluorescence microscope based on Olympus IX81 frame interfaced with a broad-band ultrafast laser system (350-670nm tunable, 85 fs, variable repetition rate). Based on a 1.4 NA oil lens, a 100x100 microns range piezo-scanner, four single photon counting avalanche photodiodes (simultaneous two color & polarization single molecule detection), PicoHarp 300 timing analyzer, attached spectrometer (Acton 2300) with back-illuminated CCD for fluorescence and Raman spectroscopy. The instrument is capable of measurements of single molecule fluorescence lifetimes (100 ps resolution), intensity, FLIM, time-resolved fluorescence and Raman spectroscopy. May be interfaced with atomic force microscope (NanoSurf).
Open frame confocal fluorescence microscope based on Olympus IX71 frame interfaced with several CW lasers (457-514nm Ar-ion tunable, He Ne 543, 594 and 632nm). Based on a 1.2 NA 60 water or 1.45 NA, 60 oil immersion lens, two avalanche photodiodes, PicoHarp 300 timing analyzer. The instrument in capable of two-color excitation, two-color detection and cross-correlation FCS, antibunching.
TIRF microscope based on Olympus IX81 frame. Uses a through-objective 1.45 NA oil immersion lens, an electron-multiplying (EMCCD) camera, dual view optical detection for FRET and colocalization studies. Uses three laser lines (488, 561 & 632nm) combined or alone, include bright field, darkfield, differential interference contrast, 2D-single molecule tracking software. Diffraction-limited spatial resolution.
Commercial multiphoton microscope based on a DM6000 frame interfaced with a MaiTai broad-band femtosecond laser. Based on several lenses including 1.2 NA 63x water and 1.4 NA 63x oil immersion lens, AOBS (optical filter free), 5 detection channels for fluorescence (PMTs), one additional channel for transmission. Capable of multiphoton fluorescence lifetime imaging (2 channels of 400 ps resolution), FLIM-FRET, confocal fluorescence imaging with conventional visible CW lasers (457, 488, 514, 543 and 632nm lines), FRET, fluorescence recovery after photobleaching, differential contrast interference.
Fluorescence lifetime pectromenter interfaced with broad-band ultrafast laser system (350-670nm tunable, 85 fs, variable repetition rate). Uses a Picoquant FT200 spectrometer with Hamamatsu microchannel plate (45 ps overall response time). Capable of measuring fluorescence lifetimes, time-resolved anisotropy, time-resolved emission spectra.