Novel fiber Bragg grating fabrication system for long gratings with independent apodization and with local phase and wavelength control

Abstract

Abstract:We proposed and demonstrated a novel practical fiber Bragg grating (FBG) fabrication setup constructed with high performance linear stages, piezoelectric translation (PZT) stages, and a highly stable continuous wave laser. The FBG fabrication system enables writing of long FBGs by a continuous translate-and-write process and allows implementation of arbitrary chirp and apodization. A key innovation is that the local Bragg wavelength is controlled by a simple movement of the phase mask by a PZT in the direction perpendicular to its surface. The focus position of the two writing beams is not changed during the Bragg wavelength change, an intrinsic feature of the design, ensuring simplicity, robustness and stability. Apodization can be achieved by vibrating the phase mask in the direction parallel to its surface by a PZT. Phase steps can also be inserted in FBGs at any desired locations by stepping the same PZT. A long uniform FBG and a linearly chirped FBG are written to demonstrate the performance of the setup.

Ultra-wide detuning planar Bragg grating fabrication technique based on direct UV grating writing with electro-optic phase modulation

“…UV writing systems for FBG inscription using phase control have been reported in the literature [8][9][10][11][12]. Mechanical methods were used to control the optical phase via piezo actuators, and the angle of incidence with stepper motors [8].…”

“…Mechanical methods were used to control the optical phase via piezo actuators, and the angle of incidence with stepper motors [8]. Individual phase masks were used in [9][10][11], which inevitably limits the flexibility and simplicity of the grating manipulation. In reference [9], an external signal was used to amplitude modulate the writing beam while the fiber was continuously translated.…”

“…However both the techniques described in [9] and [10] are limited by the 100-200µm diameter spot size which constrains the detuning bandwidth; for example in [10] the grating reflection peak uniformity reduces by 3dB within ~2.5nm from the high contrast Bragg wavelength. In an alternative approach [11], the local Bragg wavelength was detuned by moving the phase mask in the direction perpendicular to its surface using a piezoelectric translation stage. However, in this technique the ability to rapidly apodize, chirp or phase shift the grating was limited by the 1 mm spot size of the writing beam.…”

A dual-pass Mach–Zehnder interferometer filter using a TCF loop mirror for double-wavelength fiber lasers

“…In order to obtain these properties, wavelength selective filters are very important components which can reduce the mode competition and suppress the mode hopping in the lasers cavity for EDFL. Until now, the main two kinds of optical filters have been proposed to achieve dual-wavelength EDFL [5][6][7][8][9][10][11][12], namely narrow band filters and comb filters. The narrow band filters are usually composed of the fiber Bragg gratings (FBGs) [5][6][7][8][9].…”

“…The narrow band filters are usually composed of the fiber Bragg gratings (FBGs) [5][6][7][8][9]. However, the FBG fabrication needs expensive equipments including the phase masks and UV laser [9]. Correspondingly, the comb filters, such as the dual-pass Mach-Zehnder interference filter [10][11][12], high-birefringence fiber-based Sagnac loop filters [13][14][15], and the twin-core fiber filter [16,17], are also introduced into ring cavity fiber laser.…”