Wideband two-process frequency conversion under stimulated Raman adiabatic passage via a continuum of dark intermediate states

Abstract

In this paper, we propose a novel hybrid planar-channel waveguide configuration in which the channel waveguide is submerged within the planar region, with an aim to study two simultaneous three-wave mixing processes under stimulated Raman adiabatic passage. In our study, an input frequency is converted to an output frequency lying very close to or very far from the input frequency via an intermediate frequency. This frequency is in the form of a continuum of modes in the planar region, while all other frequencies propagate as guided modes of the channel waveguide. The continuum of modes at the intermediate frequency allows the simultaneous phase matching to be satisfied over a wide range of wavelengths. As a consequence, this leads to a wideband and efficient conversion from the input to the output frequency without any significant power accumulation at the intermediate stage, which is ensured through the counterintuitive and adiabatic variation in the nonlinear coupling strengths.

Efficient cascaded wavelength conversion under two-peak modulated Stark-chirped rapid adiabatic passage via grating structures

“…The adiabatic condition can be described as follows [19]: Phase reversal quasi-phase-matching (PRQPM) is used to modulate the second-order nonlinear coefficient (2)  in the optic crystals [20][21][22]. Pragati et al designed a series of structures in the optical crystal by mainly using two different quasi-phase-matching (QPM) grating structures in a hybrid planar-channel waveguide to achieve the two cascaded wavelength conversion process with STIRAP mechanism effects, and they realized the of two coupling coefficients in the construction of an adiabatic process in the action length [23]. The arrangement of the periodic inversion domain structure in the action distance affects the coupling coefficient in the process of wavelength conversion.…”