Grating formation in pure silica-core fibers

Abstract

Strong grating formation in pure silica-core fibers by use of 193-nm ArF-laser radiation is reported. Unsaturated refractive-index changes of Dn~0.3x10(-3) were observed in nontreated fiber, and changes of Dn~0.5x10(-3) were observed in fibers with a high hydroxyl concentration. Possible mechanisms of photosensitivity in pure silica-core fibers are discussed.

Role of hydrogen loading and glass composition on the defects generated by the femtosecond laser writing process of fiber Bragg gratings

“…This result concurs with the work of Albert et. al., which showed that the loading of fibers with molecular hydrogen prior to irradiation with a UV laser at 193 nm allowed for a faster and stronger grating inscription process [13]. The lack of FL features, shown in Fig.…”

“…The repetition rate of the laser was set at 100 Hz and the pulse energy was 900 μJ. With these parameters the intensity of the laser at the fiber core was ~2x10 13 W/cm 2 , below that required for type-II damage grating formation [12]. The transmission loss at the Bragg wavelength of the grating was continuously monitored with a spectrum analyzer.…”

Femtosecond pulse written fiber gratings: a new avenue to integrated fiber technology

“…However, such techniques are restricted to the fiber core and require a precise chemical finetuning in order to keep the guiding properties of the fiber intact. Grating formation in pristine fibers is not impossible, but comes at the expense of very long exposure times [25]. In particular fibers employed in todays high power lasers are a challenge to common inscription techniques: large core diameters, high rare-earth dopant concentration and aircladding or photoniccrystal geometries represent the most important obstacles for commercial FBG production.…”

Long-period gratings based on Photonics crystal fibers and applications

“…However, the single material property of PCFs leads to non-photosensitivity to UV light, therefore FBGs and LPGs cannot normally be formed in PCFs by use of the conventional UV-written technique, unless a PCF with a Ge-doped photosensitive core is used [26]. Recently, several alternative methods for making LPGs in PCFs with non-photosensitive cores were introduced, including glass structure change [27], periodic structural and/ or residual stress relaxation induced by arc discharge or a CO 2 laser [28][29][30][31][32], refractive index modulation by periodically applied mechanical pressure [33] or by the use of an acoustic wave [34,35], and periodic drilling micro-holes with a femto-second laser [36].…”