Interferometric inscription of surface relief gratings on optical fiber using azo polymer film

Abstract

We report the fabrication and characteristics of surface relief grating on the end surface of silica optical fiber with a diameter of 125 m. One-and two-dimensional gratings were inscribed on the fiber surface covered with azo polymer thin-film layer using interferometric methods. Diffraction beam patterns of the zeroth and the first order due to surface relief gratings were observed using a 635 nm laser, and the relation between the measured diffraction beam pattern and the grating period was also investigated.

The Optical Fiber Tip: An Inherently Light‐Coupled Microscopic Platform for Micro‐ and Nanotechnologies

“…However on the small fiber tip, surface tension can dominate to create curved and non‐planar coatings. Methods that have been described for coating the fiber tip with polymer include dip‐coating, dip and vibration coating, spin‐coating, spray coating, and thermal evaporation…”

“…The fabrication techniques that have been applied to fiber tips include: Planar fabrication technologies , which have been applied intrinsically and extrinsically to the fiber tip, and include photolithography, nanoimprinting, interference lithography, electron‐beam lithography, focused ion‐beam milling, two‐photon polymerization, femtosecond laser ablation, and thin‐film deposition; Hybrid techniques , which transfer micro and nano structures to the fiber tip, thereby retaining the benefits of fabricating on large planar substrates; and Through‐fiber patterning , where the optical power distribution within the fiber can create unique geometries of photosensitive material at the fiber tip . Finally, this article reviews the techniques, challenges and prospects for mass production of patterned fiber tips, where the microscopic cross‐section and inherently serial nature of the optical fiber stand in stark contrast to the large size and parallel die processing of traditional planar substrates.…”

Investigation of the Photoresist Pattern Profile Contrast Improvement in Interference Lithography Technique Using 488-nm Laser

“…The azo polymer has been used to make period structures at 488-nm laser interference lithography. Compared to conventional photoresist films, azo film can be used to produce a surface relief grating, where the actual mass of the layer is modulated rather than the reflective index [10].…”

“…For isotropic wet etching, the photosensitized resist is dissolved across the whole resist-developer interface, and the changes of developer-resist interface due to the dissolution can be described by (10) where is the dissolution rate, which can be measured experimentally, and are two vectors, and unit vector is perpendicular to the photoresist surface (11) where is the angle between the unit vector and the axis.…”

Anomalous Beam Pattern with Diffraction Grating on the End Surface of Hollow Optical Fiber

“…[2] One of the methods is the surface relief grating using azo-polymer film, where the actual mass of layer is modulated. [3] Another approach is the direct inscribing microstructures on fiber surface using femtosecond laser pulses. Formation of these photorefractive index modulation structures can provide effective diffraction grating even on very tiny region with ultra high accuracy.…”