ABSTRACT
We used an all-optical poling method to fabricate quadratic nonlinearity gratings in a tetragonal 0.62Pb(Mg1/3Nb2/3)O3-0.38PbTiO3 (PMN-38PT) crystal. We then employed these gratings in quasi-phase matched collinear second harmonic generation processes. By measuring the second harmonic output, we provided, for the first time, to the best of our knowledge, quantitative estimates of all three non-zero quadratic nonlinearity coefficients of the PMN-38PT crystal.
ABSTRACT
In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680-750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author's best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments.
