Single Molecule Spectroscopy / Ultrafast Laser Spectroscopy / Nonlinear Optical Imaging and Quantum Imaging / Optics 
  • 单粒子光谱

    单粒子光谱

  • 超快光谱学

    超快光谱学

  • 空间光束检测

    空间光束检测

  • 片上高品质因子光学微腔及应用

    片上高品质因子光学微腔及应用

Ultrafast Laser Spectroscopy

Experiments

1) Ultrafast transient absorption spectroscopy


       Ultrafast transient absorption (TA) spectroscopy studies the electronic dynamics by probing the absorption change related to photo-excitation. The technique is configured in conventional pump-probe geometry with an ultrashort laser split into two beams. The stronger beam is routed to an OPA to detune the wavelength of pump beam which excites the sample to generate a non-equilibrium state. The weaker beam is used to generate broadband supercontinuum which monitors the pump-induced changes in optical response (such as transmission or reflectivity) of the sample. The relaxation of electronic states in sample is obtained by measuring the pump-induced changes as a function of time delay between the arrival of pump and probe pulses. Our system covers the UV-Vis-NIR wavelength range with temporal resolution better than 10 fs. In addition, we synchronize a sub-ns pulse laser with the regenerative amplifier for ns-resolved TA spectroscopy. In our lab, TA spectroscopy has been employed to investigate the dynamics of light-matter interaction together with time-resolved photoluminescence spectroscopy.


2) Two-dimensional electronic spectroscopy


         Two-dimensional electronic spectroscopy (2DES) is a powerful tool for studying quantum dynamics in various material systems. We demonstrate a novel configuration for 2DES that combines the partially collinear pump-probe geometry with active phase locking by employing two non-collinear optical parametric amplifiers as the pump and probe sources. The two collinear pump pulse replicas are created using a Mach-Zehnder interferometer phase stabilized by active feedback electronics. Taking the advantage of separated paths of the two pump pulses in the interferometer, we improve the signal-to-noise ratio with double modulation of the individual pump beams. In addition, a quartz wedge pair manipulates the phase difference between the two pump pulses, enabling the recovery of the rephasing and non-rephasing signals. Our setup integrates many advantages of available 2DES techniques with robust phase stabilization, ultrafast time resolution, two-color operation, long delay scan, individual polarization manipulation and the ease of implementation.



3) Time-resolved magneto-THz spectroscopy


    Terahertz (THz) time-domain spectroscopy is a powerful tool for studying low-energy excitation in condensed matter. The technique of optical pump THz probe enables the dynamics of photo-excited non-equilibrium states. In our lab, we combine the optical pump THz probe spectroscopy with a superconducting magnet (up to 10 T) to study the dynamics of quasiparticles excited from ground states in various quantum materials.

Materials

1) Semiconductor nanocrystals

2) Organic solar cells

3) Quantum materials


Copyright © 2004-2012 Address:National Laboratory of Solid State Microstructures, Nanjing University, 22 Hankou Road, Nanjing, China (210093)