Structural long period gratings made by drilling micro-holes in photonic crystal fibers with a femtosecond infrared laser

Abstract

We present a new method for fabricating structural long-period gratings (LPGs) in photonic-crystal fibers (PCFs). The method is based on periodically drilling holes into the PCF cladding along the length of the fiber by use of a focused femtosecond infrared laser. A very short LPG with only 9 periods and a grating length of < 4 mm exhibited resonance strength of over 20 dB and a polarization dependent loss of 25 dB. The high resonance strength is attributed to the strong modulated mode-field profile caused by the significant perturbation of the fiber geometry. The mechanism of LPG formation is discussed based on coupled local-mode theory.

Alcohol sensing over O+E+S+C+L+U transmission band based on porous cored octagonal photonic crystal fiber

“…But the massive achievement occurs in different technological sectors. By the progression of the technological achievement, numerous fabrication techniques such as stack and draw process [38], extrusion [39], drilling [40], sol gel casting [41], and die cast process [42] have been proposed. The stack and draw process is generally preferable for honey comb and triangular lattices.…”

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].…”

Improved bending property of half-filled photonic crystal fiber

“…First of all, as shown in Figs. 1(a1) and 1(d), a rectangular groove with a width of about 30 µm and a depth of about 55 µm was craved on the side of the PCF by the use of a micromachining system consisting of a femtosecond laser and a microscope (Nikon ECLIPSE 80i) [22]. Consequently, about half of air holes in the PCF were exposed at the grooved section.…”