Wavelength conversion based on four-wave mixing in a highly nonlinear fiber in ring configuration

Abstract

An efficient system for generating the four-wave mixing (FWM) effect in a short length of a highly nonlinear fiber (HNLF) is demonstrated using a ring configuration, which to our knowledge is the first of its kind to be reported. The conversion efficiency obtained is -4 dB for a HNLF length of 100 m when pumped with a 90 mW diode pump laser at 1490 nm in ring configuration which is the highest ever reported. The signal-to-noise (SNR) ratio is 43 dB. The conversion efficiency and SNR are flat over a span of 20 nm and can provide an effective means of wavelength conversion for telecommunication applications.

Theory of cavity-enhanced spontaneous four wave mixing

“…2 the resulting JTI calculated numerically through Eq. (16). In physical terms, the two photons in a given pair may exit the cavity together, or may be delayed with respect to each other by a whole number of cavity round-trip times.…”

“…The spectral cavity mode structure translates into a specific temporal-mode structure. In figure 3, we have shown for the same source parameters as in figure 2 the resulting JTI calculated numerically through equation (16). In physical terms, the two photons in a given pair may exit the cavity together, or may be delayed with respect to each other by a whole number of cavity round trip times.…”

“…1(a)]. Likewise, the cavity can be in the form of a fiber ring [15][16][17], which could be implemented through a length of fiber connected to one input port and one output port of a fiber-based beam splitter and two lengths of fiber, to form the input and output of the device, connected to the remaining two ports [see Fig. 1(b)].…”

“…In addition, if implemented in a fiber, SFWM has a number of important advantages including the possibility of very long interaction lengths and straightforward integration with existing fiber optic networks. Recently, in the context of classical optics there have been important experimental demonstrations of four wave mixing (FWM) [14] and the implementation of nonlinear optical devices, such as wavelength converters and multi-wavelength fiber lasers, which are based on FWM [15][16][17][18][19]. While the use of a guided-wave configuration constrains the transverse spatial properties of emitted photon pairs, the spectral properties can vary widely.…”

“…A χ (3) SFWM cavity source can be implemented with an optical fiber on which two Bragg gratings are recorded to form a cavity (see figure 1(a)). Likewise, the cavity can be in the form of a fiber ring [15][16][17], which could be implemented through a length of fiber connected to one input port and one output port of a fiber-based beam splitter and two lengths of fiber, to form the input and output of the device, connected to the remaining two ports (see figure 1(b)). Alternatively, recent work has shown the feasibility of observing optical nonlinear effects in waveguide micro-rings, where light is coupled and out-coupled from the cavity through a straight waveguide placed tangentially to the ring [35].…”