Bandpass filter with adjustable bandwidth based on a press-induced long-period twisted holey-fiber grating

Abstract

A bandpass filter with adjustable bandwidth based on a press-induced long-period grating in a twisted holey fiber is presented. By twisting the holey fiber prior to the application of periodic pressure, each rejection band of the nontwisted induced long-period grating is split into two shifted rejection bands that move further apart as the twist ratio increases. This feature results in a wide bandpass filter with controllable bandwidth. A bandpass filter at 1523 nm with adjustable bandwidth from 15 to 65 nm with near-linear response and insertion loss lower than 0.7 dB is demonstrated. Additionally, the bandpass filter can be tuned over 100 nm.

Mechanically-Induced Long-Period Fiber Gratings Using Laminated Plates

“…Furthermore, a low uniaxial pressure noticeably reduces the probability of failure in the optical fiber. In this sense, lower uniaxial pressures can be used to inscribe MI-LPFGs by laminated plates, where the results are of great interest in distinct applications [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. On the other hand, the normalized transmission of the leading rejection bands shows similar behavior with respect to the rejection bands in conventional LPFGs, as depicted in Figure 5 d, where one can find good correlation between the experimental results and the theory.…”

“…Additionally, MI-LPFGs are wide tunable with flexible control of depth attenuation and bandwidth of the rejection bands, and they are reversible. These properties make MI-LPFGs attractive for actual uses, such as variable gain shapers, mode converters, wavelength filters, and sensors, among other applications [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ].…”