Researchers experimentally demonstrate flexible and customizable filtering of broadband optical signals using chirped and tilted fiber Bragg grating technique
In optical fibers, fiber Bragg grating (FBG) functions as band-rejection filter that reflects specific wavelengths of light while allowing others to pass unimpeded, offering advantages such as improved signal transmission quality, reduced signal loss, and high signal specificity for sensing applications. There are several types of FBGs, including uniform FBG (UFBG), chirped FBG (CFBG), tilted FBG (TFBG) and long-period fiber grating (LPFG). However, these techniques are not suitable for filtering optical signals with large bandwidths efficiently.
Researchers from Shenzhen University have now experimentally demonstrated the viability of chirped and tilted fiber Bragg grating (CTFBG) for flexible and adjustable wavelength filtering in broadband optical signals. Published in Journal of Lightwave Technology, their findings highlight the potential of CTFBG-based band-rejection filters for a range of advanced optical applications.
“The CTFBGs have the advantages of large filtering bandwidth (up to more than 100 nm), high filtering slope efficiency and exceptional broadband tunability, which makes them increasingly used in high-quality band-rejection filtering, edge filtering, and gain equalizers,” explains Dr. Fan.
The study shows that CTFBGs have several advantages as a band-rejection filter for broadband optical signals besides flexibility and precise filtering performance. For example, the researchers have shown that these FBGs have low insertion loss, high filtering efficiency, and negligible back-reflection. Furthermore, they demonstrated high resilience to changes in the environment and stress in these FBGs.
“The experimental results show that this filter is insensitive to temperature, axial strain and bending. The CTFBGs fabricated by LBL technology show significant improvements in spectral tailoring and coating maintaining, making it a great candidate for high-quality band rejection filtering, edge filters and gain equalizers,” Dr. Fan concludes.
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