Abstract
In this paper, we study a photonic Bragg waveguide sensor for resonant sensing applications in the THz range. In order to enhance the resolution and detectivity of the sensor, we modify the relatively broad transmission spectrum of the Bragg waveguide with spectrally narrow transmission dips by creating a geometrical defect in Bragg reflector and causing anti-crossing phenomenon between the core-guided mode and defect mode. The spectral position of the resonant dip is highly sensitive to the thickness variation in the vicinity of the waveguide core. By designing and manufacturing a Bragg waveguide which includes several sections with different defect layer thicknesses, we can interrogate more than one sample simultaneously and thereby realize multichannel resonant sensing by directly tracking the independent resonant dips. Furthermore, we demonstrate the waveguide platform for online monitoring of the thickness variation of lactose powders, which is captured on the waveguide core via a centrifugal force using a home-built rotating setup. Additionally, we also demonstrate the waveguide for fingerprint detection of powder analytes, which further enriches the sensing scenario of the sensing platform. Finally, we discuss the advantages and the spectral tailoring flexibility of the THz Bragg waveguides sensors for future implementations.
Highlights
Over the past decades, ultrasensitive optical sensing based on engineered structures with resonant sensing features has attracted considerable interests in a variety of fundamental and practical applications [1,2,3,4,5]
The developed waveguide sensor is based on resonant phenomenon between the coreguided and defect modes localized in the defect layer, it is more advantageous and robust than traditional free-space-transmission-mode spectroscopy for layer thickness measurement, which records the phase variations in the THz waves passing through a thin film
In our method, the relatively broad transmission window of the Bragg waveguides is modified by spectral narrow loss peaks, which enables resolving minute spectral shift caused by small changes in the defect layer thickness of refractive index
Summary
Ultrasensitive optical sensing based on engineered structures with resonant sensing features has attracted considerable interests in a variety of fundamental and practical applications [1,2,3,4,5]. In order to extend the probing depth of the surface wave to longer distance for macromolecular or bacteria detection, one solution is to develop resonant sensors operating at longer wavelengths (such as THz). The THz range, with frequencies lying between 100GHz and 10THz, has strong application potential for a wide range of industrial and scientific fields, including biosensing, imaging, communications, and spectroscopy [6,7,8,9]. Among these applications, THz biosensing has attracted considerable interest due to many appealing properties of THz waves. The probing length of THz surface wave is a natural candidate for detection of macromolecules, cells, and bacteria of relatively large sizes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
