Radio-frequency ring resonators for self-referencing fiber-optic intensity sensors

Abstract

Abstract.A theoretical and experimental study of radiofrequency ring resonators (RR) for referencing and improving the sensitivity of fiber-optic intensity sensors (FOS) is reported. The separation between lead and transducer losses in the FOS is solved by converting the light intensity fluctuations to be measured into RR losses that produce high amplitude variations in the proximity of the RR resonance frequencies. Two different self-referencing techniques are developed. Via the definition of the measurement parameter R M , sensor linearity and sensitivity are analyzed. A calibration using an optical attenuator is reported to validate the model.

Self-referencing techniques in photonics sensors and multiplexing

“…In order to neutralize all these effects, a variety of selfreferencing techniques for intensity sensors have been reported [3][4][5][6][7][8][9][10][11].…”

“…Different configurations such as ring resonators operating under incoherent regime have been proposed The RR selfreferencing technique in a transmission configuration [6,8] is made of a RR with an optical fiber sensor, FOS, in the loop which it is placed at each remote measuring point. A scheme of this configuration can be seen in Figure 3.…”

“…Spatial referencing is the simplest to implement with the reference and measurand signals being located within two separated optical fibers [2]; but it is difficult to ensure similar common-mode variations in two separated fibers. Time division [3], wavelength normalization [4], spectral splitting [5], frequency-based self-referencing methods on differential amplitude [6][7][8][9] or using amplitude to phase conversion [10], and others using counter propagating signals [11] or electronic means [12] have been reported to overcome this problem.…”

“…In terms of sensor linearity, the RR is not a very favorable configuration, unless the measuring range covers a small variation in H [8]. In many cases the FOS itself is not linear, so this should not be considered a constraint.…”

CWDM self-referencing sensor network based on ring resonators in reflective configuration

“…Additionally, random power fluctuations of optical sources at the input of the network and detector sensitivity changes can induce an intensity noise added to the desired signals. In order to neutralize all these effects, a variety of self-referencing techniques for intensity sensors have been reported using Michelson and Mach-Zehnder configurations [1] with multimode (MM) fibres, and RR configurations with single mode (SM) [2] and plastic optical fibres [3].…”