Properties of a hollow-core photonic bandgap fiber at 850 nm wavelength

122

102

Long period fiber gratings in hollow-core air-silica photonic bandgap fibers were produced by use of high frequency, short duration, CO 2 laser pulses to periodically modify the size, shape and distribution of air holes in the microstructured cladding. The resonant wavelength of these gratings is highly sensitivity to strain but insensitive to temperature, bend and external refractive index. These gratings can be used as stable spectral filters and novel sensors.

Section: Mechanism Of Lpfg Formationmentioning

confidence: 99%

Long period gratings in air-core photonic bandgap fibers

Wang¹,

Jin²,

Ju³

et al. 2008

122

102

“…As have been shown previously, HC-PBFs have considerable residual birefringence due to the imperfect non-centro-symmetry resulted from the fiber fabrication process [19,20]. The birefringence existing in the HC-1550-2 PCF results in accumulated phase difference between the two orthogonal polarization modes when they propagate along the PBF, and this is the basis for the stable operation of the in-fiber PMI.…”

Section: Operating Principle and Fabrication Of Pmimentioning

confidence: 76%

In-fiber polarimeters based on hollow-core photonic bandgap fibers

Xuan¹,

Jin²,

Zhang³

et al. 2009

In-fiber polarimeters or polarization mode interferometers (PMIs) are fabricated by cascading two CO2-laser-induced in-fiber polarizers along a piece of hollow-core photonic bandgap fiber. Since the two interfering beams are the orthogonal polarizations of the fundamental mode, which are tightly confined to the core and have much lower loss than higher order modes, the PMIs can have either short (e.g., a few millimeters) or long (tens of meters or longer) device length without significantly changing the fringe contrast and hence provide design flexibility for applications required different device lengths. As examples of potential applications, the PMIs have been experimentally demonstrated for wavelength-dependent group birefringence measurement; and for strain, temperature and torsion sensors. The PMI sensors are quite sensitive to strain but relatively insensitive to temperature as compared with fiber Bragg grating sensors. The PMIs function as good directional torsion sensors that can determine the rate and direction of twist at the same time.

“…The highest measurable dispersion, in this case about ±1000 ps/nm/km, is determined by the resolution of the OSA. It should be noted that 7 cell PBGFs are slightly multimode [17] and indeed several secondary interferograms, produced by higher order core modes, were observed to overlap with the primary interferogram of the fundamental (LP 01 -like) mode. Whilst their intensity could be minimized by optimizing the input coupling, they could not be completely eliminated and their presence produced a slightly higher level of noise as compared, e.g.…”

Section: Dispersion Measurement Of Key Mof Fiber Typesmentioning

confidence: 98%

Fast and broadband fiber dispersion measurement with dense wavelength sampling

Ponzo¹,

Petrovich²,

Feng³

et al. 2014

Abstract:We report on a method to obtain accurate dispersion measurements from spectral-domain low-coherence interferograms, which enables high accuracy (~ps/nm/km), broadband measurements and the determination of very dense (up to 20 points/nm over 500 nm) datasets for both dispersion and dispersion slope. The method exploits a novel phase extraction algorithm which allows the phase associated with each sampling point of the interferogram to be calculated and provides for very accurate results as well as a fast measurement capability, enabling close to real time measurements. The important issue of mitigating the measurement errors due to any residual dispersion of optical elements and to environmental fluctuations was also addressed. We performed systematic measurements on standard fibers which illustrate the accuracy and precision of the technique, and we demonstrated its general applicability to challenging problems by measuring a carefully selected set of fibres: a lead silicate microstructured fiber with a flat, near-zero dispersion profile; a hollow core photonic bandgap fiber with strongly wavelength-dependent dispersion and dispersion slope; a small core, highly birefringent index guiding microstructured fiber, for which polarization resolved measurements over an exceptionally wide (~1000 nm) wavelength interval were obtained. 2013 Optical Society of America