scholarly journals NIR-to-NIR Imaging: Extended Excitation Up to 2.2 μm Using Harmonic Nanoparticles with a Tunable hIGh EneRgy (TIGER) Widefield Microscope

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3193
Author(s):  
Laura Vittadello ◽  
Jan Klenen ◽  
Karsten Koempe ◽  
Laura Kocsor ◽  
Zsuzsanna Szaller ◽  
...  

Near-infrared (NIR) marker-based imaging is of growing importance for deep tissue imaging and is based on a considerable reduction of optical losses at large wavelengths. We aim to extend the range of NIR excitation wavelengths particularly to values beyond 1.6 μm in order to profit from the low loss biological windows NIR-III and NIR-IV. We address this task by studying NIR-excitation to NIR-emission conversion and imaging in the range of 1200 up to 2400 nm at the example of harmonic Mg-doped lithium niobate nanoparticles (i) using a nonlinear diffuse femtosecond-pulse reflectometer and (ii) a Tunable hIGh EneRgy (TIGER) widefield microscope. We successfully demonstrate the existence of appropriate excitation/emission configurations in this spectral region taking harmonic generation into account. Moreover, NIR-imaging using the most striking configurations NIR-III to NIR-I, based on second harmonic generation (SHG), and NIR-IV to NIR-I, based on third harmonic generation (THG), is demonstrated with excitation wavelengths from 1.6–1.8 μm and from 2.1–2.2 μm, respectively. The advantages of the approach and the potential to additionally extend the emission range up to 2400 nm, making use of sum frequency generation (SFG) and difference frequency generation (DFG), are discussed.

2014 ◽  
Vol 989-994 ◽  
pp. 3790-3793
Author(s):  
Hai Dong Wu ◽  
Jin Song Guo ◽  
Yun Wen Wu ◽  
Zhao Xia Wang

Bandwidth enhancement and response flattening of wavelength conversion based on single-pass and double-pass cascaded second harmonic generation and difference frequency generation in step-segmented quasi-phase matched (QPM) gratings are investigated. For the same waveguide length, high conversion efficiency, flat response and broad signal bandwidth can be obtained simultaneously by optimizing the poling period of the step-segmented QPM structure. The conversion bandwidths in a 3-cm-long five-step-segmented waveguide are 134 nm for single-pass scheme and 132 nm for the double-pass one, respectively, which are both over the whole conventional band and long-wavelength band. The ripple on the matching response can keeps less than 0.2 dB as well.


2011 ◽  
Vol 84 (23) ◽  
Author(s):  
Sarina Wunderlich ◽  
Benedikt Schürer ◽  
Christian Sauerbeck ◽  
Wolfgang Peukert ◽  
Ulf Peschel

1996 ◽  
Author(s):  
Valery V. Badikov ◽  
P. F. Gonzalez-Diaz ◽  
Magna G. Santos ◽  
C. L. Siguenza ◽  
Galina S. Shevyrdayeva ◽  
...  

1995 ◽  
Vol 04 (02) ◽  
pp. 459-495 ◽  
Author(s):  
Y. H. JIN ◽  
X.-C. ZHANG

We present experimental measurements of Terahertz optical rectification in electro-optic crystals. The measured data was compared with a simple theoretical analysis (anharmonic oscillator model). We also measured Terahertz-bandwidth subpicosecond electromagnetic radiation via nearly-degenerate difference-frequency generation in electrooptic materials. The variation in Terahertz emission with crystal orientation demonstrated that the generation of Terahertz radiation via optical rectification involves a bulk second-order nonlinear process. We studied Terahertz optical rectification from zincblende crystals as the incident photon energy was tuned across the semiconductor optical absorption band-edge (resonant excitation). We also present the measurement of temperature-dependent Terahertz optical rectification. A comparison between the two second-order nonlinear processes, sum-frequency generation (second-harmonic generation) and different-frequency generation (optical rectification) is presented.


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