Abstract
Two slightly shifted wavelength Bragg gratings are inscribed one over the other in a single mode fiber, by moving the phase-mask (PM) between two positions. The inscription setup includes a NIR femtosecond laser, a PM, a defocusing spherical lens and a cylindrical focusing lens. A first fiber Bragg grating (FBG) is inscribed, while the second overlapping FBG is inscribed only after a slight movement of the PM, enabling a slight wavelength shift. The transmission spectrum of the complex structure is like that of a phase-shifted fiber Bragg grating (PSFBG), while the inscription process is very fast and simple compared to other standard methods. A high-quality PSFBG with two −22 dB transmission dips, and a central 16 dB transmission peak with a 30 pm transmission bandwidth at 3 dB is achieved. It is also observed that this PSFBG structure is birefringent. Finally, the temperature and strain sensitivities of the PSFBG are experimentally measured and are 10.8 pm/°C and 0.8 pm/µɛ, respectively.
| Original language | English |
|---|---|
| Article number | 102689 |
| Journal | Optical Fiber Technology |
| Volume | 67 |
| DOIs | |
| State | Published - 1 Dec 2021 |
Keywords
- Femtosecond inscription
- Fiber Bragg gratings
- Optical fibers
- Phase shifted gratings
ASJC Scopus subject areas
- Control and Systems Engineering
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Instrumentation
- Electrical and Electronic Engineering