Frequency conversion of CO₂laser radiation to the 0.5μrange in nonlinear crystals

Abstract

Distributional sources of matter on codimension-two and higher branes are only well-defined as regularized objects. Nevertheless, intuition from effective field theory suggests that the low-energy physics on such branes should be independent of any highenergy regularization scheme. In this paper, we address this issue in the context of a scalar field model where matter fields (the standard model) living on such a brane interact with bulk fields (gravity). The low-energy effective theory is shown to be consistent and independent of the regularization scheme, provided the brane couplings are renormalized appropriately at the classical level. We perform explicit computations of the classical renormalization group flows at tree and one-loop level, demonstrate that the theory is renormalizable against codimension-two divergences, and extend the analysis to several physical applications such as electrodynamics and brane localized kinetic terms.

Efficient frequency upconversion of coherent radiation from 10.26 to 1.187μm in a GaSe crystal

“…A short-pulse repetition-frequency-excited waveguide CO 2 laser emitting the wavelength of 10.26 lm as an input beam was frequency-upconverted to an output beam at 1.187 lm inside a GaSe crystal, in the presence of the radiation generated by an ultra-compact Q-switched Nd:YAG laser at 1.064 lm. We would like to note that this parametric process is different from that studied previously [1,2,[6][7][8][9]. Specifically, our frequency upconversion is achieved through DFG whereas in the previous publications sum-frequency generation (SFG) was employed [1,2,[6][7][8][9].…”

“…We would like to note that this parametric process is different from that studied previously [1,2,[6][7][8][9]. Specifically, our frequency upconversion is achieved through DFG whereas in the previous publications sum-frequency generation (SFG) was employed [1,2,[6][7][8][9]. We have chosen such a process since the longpass filters are very effective in removing the un-converted laser beam at 1.064 lm.…”

“…Previously, several nonlinear-optical crystals [5], including AgGaS 2 [6], ZnGeP 2 [7], and GaSe [8,9], were used to demonstrate frequency upconversion. Among these crystals, the absorption coefficient around 10 lm is the highest for ZnGeP 2 [5] due to two-phonon absorption [10].…”