Abstract
In this paper we show that by suitably tailoring the dispersion characteristics of a Bragg reflection waveguide (BRW) mode, it is possible to achieve efficient photon pair generation over a large pump bandwidth while maintaining narrow signal bandwidth. The structure proposed consists of a high index core BRW with a periodically poled GaN core and periodically stratified cladding made up of alternate layers of Al(0.02)Ga(0.98)N and Al(0.45)Ga(0.55)N. Such photon-pair generators should find applications in realizing compact and stable sources for quantum information processing.
Highlights
Efficient generation of entangled photon pairs using spontaneous parametric downconversion (SPDC) have been the key ingredient for a number of quantum optics experiments, ranging from testing the foundations of quantum mechanics to various quantum communication applications such as quantum cryptography [1] and quantum teleportation [2,3,4] over long distances
In this paper we show that by suitably tailoring the dispersion characteristics of a Bragg reflection waveguide (BRW) mode, it is possible to achieve efficient photon pair generation over a large pump bandwidth while maintaining narrow signal bandwidth
One could think of a heralded single photon source in which the broadband photon is detected, using an upconversion-based or a superconducting detector [22,23], in order to announce the arrival time of the associated narrowband signal photon at the end of the quantum communication channel [24]
Summary
Efficient generation of entangled photon pairs using spontaneous parametric downconversion (SPDC) have been the key ingredient for a number of quantum optics experiments, ranging from testing the foundations of quantum mechanics to various quantum communication applications such as quantum cryptography [1] and quantum teleportation [2,3,4] over long distances. We define the pump acceptance bandwidth (BW) of any downconverter as the spectral width over which the conversion efficiency remains higher than half its maximum value at a chosen signal wavelength. On the other hand, increasing for instance the length of a non-linear waveguide would increase the conversion efficiency but the signal BW would still be substantially broad due to near identical dispersion characteristics of the signal and idler modes. In the latter case, using a broadband pump would usually result in a very broad spectrum of the generated signal photons which is inescapably submitted to fiber chromatic dispersion as reported in Refs. Fujii et al [8] have experimentally demonstrated the generation of narrowband signal photons (∼ 1 nm BW for 30 mm long waveguide) using type-II interaction in a periodically poled lithium niobate waveguide
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