Study of transmission response of edge filters employed in wavelength measurements

Applied Optoelectronics Centre, School of Electronics and Communications Engineering, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
Applied Optics (Impact Factor: 1.69). 01/2006; 44(36):7789-92. DOI: 10.1364/AO.44.007789
Source: PubMed

ABSTRACT The ratiometric wavelength-measurement system is modeled and an optimal design of transmission response of the employed edge filter is demonstrated in the context of a limited signal-to-noise ratio of the signal source. The corresponding experimental investigation is presented. The impact of the limited signal-to-noise ratio of the signal source on determining the optimal transmission response of edge filters for a wavelength-measurement application is shown theoretically and experimentally. (c) 2005 Optical Society of America.

  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel scheme for a code-division multiplexing based fiber Bragg grating sensor system is theoretically analyzed and experimentally demonstrated. The results show that the proposed scheme enables an improved signal-to-noise ratio performance compared with the time-division multiplexing method and that spontaneous–spontaneous beating noise should be included in the analysis to avoid overestimation. The simple and effective setup provides a competitive approach for using fiber Bragg grating sensors in practical application systems.
    Fiber and Integrated Optics 05/2014; 33(1-2). DOI:10.1080/01468030.2014.893041 · 0.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The application of microfibre couplers in a comb-filter-based ratiometric wavelength measurement system is discussed. The fabrication of microfibre coupler is presented and its temperature-dependent performance is investigated. The resolution of the ratiometric wavelength measurement system with a microfiber coupler is significantly improved in comparison with a conventional ratiometric system to better than 4 pm maintaining the potential for high measurement speed and wide measurable wavelength range.
    Photonics and Optoelectronics (SOPO), 2012 Symposium on; 01/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This thesis describes theoretical and experimental investigations on all-fibre multimode interference (MMI) devices using a singlemode-multimode-singlemode (SMS) fibre structure for use as a new type of edge filter for a ratiometric wavelength measurement system and as novel stand alone sensors. The use of two edge filters, so called X-type edge filters based on SMS fibre structures in a ratiometric wavelength measurement system is proposed and demonstrated. The use of X-type edge filters can improve the resolution and accuracy of wavelength measurement compared to the use of one edge filter in a conventional ratiometric system. Several aspects of the SMS edge filters have been investigated, including the effect of misalignment the SMS fibre cores due to fabrication tolerances, polarization dependence, and temperature dependence. These aspects can impair the performance of a ratiometric wavelength measurement system. Several approaches have been proposed and demonstrated to achieve high resolution and accuracy of wavelength measurement. Misalignment effects due to the splicing process on the spectral characteristics and PDL of SMS fibre structure-based edge filters are investigated numerically and experimentally. A limit for the tolerable misalignment of the cores of an SMS fibre structure-based edge filter is proposed, beyond which the edge filter’s spectral performance degrades unacceptably. It is found that a low PDL for an SMS fibre structure-based edge filter can be achieved with small lateral core offsets. Furthermore, the rotational core offsets position is proposed to minimize the PDL. Analysis of the temperature dependence of SMS X-type edge filters is presented. The temperature variation in the system can be determined and compensated by using an expanded ratiometric scheme with an additional reference arm. New sensing applications of multimode interference in an SMS fibre structure are proposed and demonstrated as a temperature sensor, a voltage sensor based on the strain effect, and a strain sensor with very low temperature dependence. All the sensors utilize a simple intensity-based interrogation system using a ratiometric power measurement system. It is found that the temperature and strain characteristics of SMS fibre structures are linear in nature and can be used for temperature and strain sensors. Based on the strain effect in an SMS fibre structure, a voltage sensor is also proposed. The SMS fibre structure is attached to a piezoelectric (PZT) stack transducer. The displacement of the PZT due to the voltage induces a strain on the SMS fibre structure and in turn results in a change in the ratio response. Finally, a strain sensor with very low temperature induced strain measurement error is investigated. For this purpose two SMS fibre structures were proposed and demonstrated in a ratiometric power measurement scheme, one SMS structure acts as the strain sensor and the other SMS structure acts as the temperature monitor. The use of this configuration can effectively minimize the temperature induced strain measurement error.

Full-text (2 Sources)

Available from
May 29, 2014