Spatially single mode photon pair source at 800 nm in periodically poled Rubidium exchanged KTP waveguides

Abstract

Photon pair sources in the visible to NIR wavelength region play a key role in quantum optics. The wavelength range around 800 nm provides an opportunity for using low cost detectors, which makes it highly interesting for practical, large scale quantum applications. Here, we report on the realization of single mode Rubidium (Rb) exchanged waveguides in periodically poled (PP) Potassium Titanyl Phosphate (Rb:KTiOPO4 or Rb:KTP) for frequency-non-degenerate type II parametric down-conversion pumped at 400 nm and generating pairs of photons at around 800 nm. The source exhibits a nonlinear conversion efficiency of 2.0%/(Wcm2), estimated from SHG measurements. Characterisation of the generated two-photon state confirms nonclassical photon-number correlations, characterized by g(1,1). The high nonlinear conversion efficiency and low temperature sensitivity make this source a promising candidate for operations in both classical and quantum integrated network applications.

Flexible source of correlated photons based on LNOI rib waveguides

“…Creating a single-mode regime is challenging, for example, such a regime cannot be designed in lithium niobate waveguides without an additional filtration due to a specific mode dispersion profile. Recently, specially engineered periodically poled titanil phosphate (PPKTP) waveguides [33,34] or even more complex configurations, highly pumped SU(1,1) interferometers [35], have been utilized for this purpose. At the same time, the use of a CW laser in both configurations makes it possible to generate spectrally multimode light, which is very important for frequency comb generating [36,37], and quantum information encoding due to a high number of vacant communication channels.…”

DC Ionic Conductivity in KTP and Its Isomorphs: Properties, Methods for Suppression, and Its Connection to Gray Tracking

“…We assume this behaviour is induced by the already-reduced ionic conductivity of the rubidium doping. Because the gray tracking occurs through high-voltage pulses, one has to be cautious that this phenomenon can occur during high-voltage operations, e.g., in optical modulators or periodic poling [11].…”

“…Thus, ionic conductivity values have to be compared at the same field strength. The ionic conductivity of KTP is a significant drawback, which restrains its applicability for operations with DC or slowly varying electric fields, like for periodic poling [11] or electro-optical modulation [12]. For this reason, the characterisation of ionic conductivity and understanding how to manipulate it are of paramount importance to fully exploit the properties of this class of materials [13].…”

Measuring higher-order photon correlations of faint quantum light: a short review

“…Natural phasematching is achieved if k p = k s − k i , which is possible for example in the semiconductor Bragg-reflection waveguides basing on modal phasematching [150]. In periodically poled waveguides and crystals a wavevector mismatch (k p −k s −k i 0) can be compensated with an artificial wavevector component that can be used for example for frequency tuning [151,152].…”