Transient Grating Spectroscopy

Transient grating spectroscopy (TGS), also known as a laser-induced transient grating (LITG) technique, is a non-destructive pump-probe technique that utilizes laser interference instead of a single laser beam to excite the sample for evaluation of the exciton lifetime and diffusion coefficient.

In this case, two interfering laser beams create a standing wave on the surface of the sample – a transient grating. The depth of absorption modulation is measured by a delayed probe beam, diffracting from the grating. The modulation depth decays as quasiparticles propagate along the excitation density gradient. The rate of decay corresponds to the diffusion of the quasiparticles. If the grating period is varied, the technique provides detailed information on the dynamics of propagation.

Moreover, LITG enables direction-dependent measurements of exciton diffusion in anisotropic materials. It is proven to be fully applicable for studying exciton and charge dynamics in crystalline media, such as bifluorene single crystals. The knowledge of the directionality of exciton diffusion is essential for the optimal crystal orientation in various devices, e.g., crystal-based organic lasers.

LITG can be realized using HARPIA-TG transient grating spectrometer pumped by PHAROS and CARBIDE femtosecond lasers. Light Conversion has managed to adapt its high-level mechanical and optical engineering solutions gathered over almost 30 years of experience in the field of lasers and laser systems to offer a simple, fully automated, and user-friendly transient grating spectroscopy system.

  • Carrier diffusion coefficient in a matter of minutes!
  • Non-invasive measurement technique
  • Fully automated and computer controlled
  • Continuous setting of grating period
  • Sensitivity down to µJ/cm² excitation level
  • 100 fs – 20 ps tunable pulse duration
  • 4 mJ maximum pulse energy
  • 20 W maximum output power
  • Single-shot – 1 MHz repetition rate
  • BiBurst
  • Automated harmonic generators (up to 5th harmonic)
  • 190 fs – 20 ps tunable pulse duration
  • 2 mJ maximum pulse energy
  • 80 W maximum output power
  • Single-shot – 2 MHz repetition rate
  • BiBurst
  • Air-cooled version
  • Tunable or fixed-wavelength models
  • Industrial-grade design
  • Plug-and-play installation and user-friendly operation
  • Single-shot – 2 MHz repetition rate
  • Up to 40 W pump power
  • < 100 fs pulse duration
  • 515 nm, 343 nm, 258 nm, and 206 nm outputs
  • Simple selection of active harmonic
  • Simultaneous or switchable outputs
  • Customizable or high-power and -energy models

Comparison of growth interruption and temperature variation impact on emission efficiency in blue InGaN/GaN MQWs

J. Mickevičius, K. Nomeika, M. Dmukauskas, A. Kadys, S. Nargelas, and R. Aleksiejūnas, Vacuum 183, 109871 (2021).

Direct observation of large electron–phonon interaction effect on phonon heat transport

J. Zhou, H. D. Shin, K. Chen, B. Song, R. A. Duncan, Q. Xu, A. A. Maznev, K. A. Nelson, and G. Chen, Nature Communications 1 (11) (2020).

Impact of Alloy-Disorder-Induced Localization on Hole Diffusion in Highly Excited c -Plane and m -Plane ( In , Ga ) N Quantum Wells

R. Aleksiejūnas, K. Nomeika, O. Kravcov, S. Nargelas, L. Kuritzky, C. Lynsky, S. Nakamura, C. Weisbuch, and J. S. Speck, Physical Review Applied 5 (14) (2020).

Extreme radiation resistance in InN

Y. Podlipskas, J. Jurkevičius, A. Kadys, M. Kolenda, V. Kovalevskij, D. Dobrovolskas, R. Aleksiejūnas, and G. Tamulaitis, Journal of Alloys and Compounds 789, 48-55 (2019).

Direct Auger recombination and density-dependent hole diffusion in InN

R. Aleksiejūnas, Y. Podlipskas, S. Nargelas, A. Kadys, M. Kolenda, K. Nomeika, J. Mickevičius, and G. Tamulaitis, Scientific Reports 1 (8) (2018).

Exciton diffusion in bifluorene single crystals studied by light induced transient grating technique

P. Baronas, P. Ščajev, V. Čerkasovas, G. Kreiza, P. Adomėnas, O. Adomėnienė, K. Kazlauskas, C. Adachi, and S. Juršėnas, Applied Physics Letters 3 (112), 033302 (2018).

Impact of carrier localization and diffusion on photoluminescence in highly excited cyan and green InGaN LED structures

K. Nomeika, R. Aleksiejūnas, S. Miasojedovas, R. Tomašiūnas, K. Jarašiūnas, I. Pietzonka, M. Strassburg, and H. J. Lugauer, Journal of Luminescence 188, 301-306 (2017).