Microstructured optical fibre with 16 linearly arrayed antiguided cores fabricated through stacking

A microstructured optical fibre with a linear-array of 16 antiguided cores was fabricated using the stacking technique. Coherent near-field guidance was observed in a 20 cm-long straight fibre. Proposals are made for achieving high-power laser output in this new type of antiguided multicore fibre on the basis of sensitivity to bending.     

Strain-induced birefringence in a highly birefringent optical fibre

A simple theory to explain the strain-induced birefringence in a highly birefringent fibre with an arbitrary cross-sectional geometry is presented. The effects caused by the distributions of Young's modulus and Poisson's ratio in the fibre are highlighted. The phase difference due to the strain-induced birefringence is found to be approximately 20 times larger than that due to the change of fibre length for typical silica-based glass fibres.<>     

Finite-element analysis of birefringence in azymuthally inhomogeneous optical fibre

This communication reports the existence of a general purpose finite-element analysis program which can be used for the analysis of stress-induced birefringence in a single-mode optical fibre. This is applied to the azimuthally inhomogeneous fibre and it is found that the stress-induced birefringence is an order of magnitude larger than the geometric birefringence in the vicinity of V = 2. Maximum birefringence occurs when equal segments of different indices are used in the core.     

High birefringence fibre interrogating interferometer for optical sensing applications

The use of high birefringence fibre forming a differential path interferometer as an interrogation unit for heterodyne fibre optic sensing applications is described.     

Continuously tunable bandpass filtering using high-index inclusion microstructured optical fibre

A tunable bandpass filter is demonstrated by applying a variable thermal gradient to a microstructured fibre with high index inclusion, thus chirping its local anti-resonances. The width of its transmission bands can be continuously varied and transmission completely suppressed. The experiment is compared with numerical simulations.     

Circular birefringence in helical-core fibre

Circular birefringence in an isotropic helical fibre is studied using coupled-mode analysis. The formulas derived here can be used to explain the existing paradox in calculating circular birefringence.     

N × N optical cross-connect based on tunable fibre Bragggratings with high channel scalability

A highly channel-scalable N × N optical cross-connect (OXC) based on tunable fibre Bragg gratings is proposed. The channel scalability of the proposed OXC is owing to cascadability of individual routing modules which perform routing only for specified wavelength channels. The routing function of a 3 × 3 routing block of the proposed OXC using four OC-192 channels with a channel spacing of 0.8 nm is demonstrated, as is the upgradability of the number of ports and wavelength channels     

Microstructured fibre Bragg gratings: analysis and fabrication

A microstructured fibre Bragg grating that relies on a partial and localised etching of the cladding layer along the grating region is proposed. The main effect is the formation of defect states inside the bandgap depending on surrounding refractive index. This leads to the possibility of realising novel optoelectronic devices for sensing and telecommunication applications.     

High birefringence fibre Bragg gratings written in tapered photonic crystal fibre with femtosecond IR radiation

High birefringence Bragg gratings were written with ultrafast 800 nm radiation in non-birefringent pure silica core photonic crystal fibres (PCF) that were tapered with an oxy-hydrogen flame. The grating spectra indicate that a birefringence above 10^-3 was created in the tapered PCF     

Radiation resistant optical fiber with a high birefringence

A radiation resistant optical fiber with a high birefringence is fabricated on the basis of nitrogen-doped silica glass using the PANDA technology and studied. The loss in this fiber for an absorbed @[gamma]-radiation dose of 2–10 kGy does not exceed 5–10 dB/km, which is an order of magnitude lower than that of standard telecommunication fibers with a germanium silicate core.     

Radial birefringence in optical resonators

Paraxial fields polarized in the transverse plane and represented in the polar coordinate system are expanded in an azimuthal Fourier series. For series terms with spiraling phases, the radial and azimuthal components are shown to mix during propagation. For simple rod lasers with thermally induced birefringence, this property may cause the dominant mode to be of mixed polarization rather than purely radial polarization. An explanation is given in terms of the properties of scalar field propagators and the way in which they combine to propagate the vector field components. Comparisons to other recent predictions show that the theory is correct, and the method provides a basis for understanding the complex results     

Inline tunable etalon filter for optical channel selection in highdensity wavelength division multiplexed fibre systems

Reports an inline angle-tuned Fabry-Perot etalon for optical channel selection in a high-density wavelength division multiplexed (WDM) direct-detection experiment. Feasibility is demonstrated in experiments with two different etalons: one for 5 distributed feedback (DFB) lasers in the 1550 nm region (1527-1559 nm), each spaced by 8 nm, and the other for 12 lasers (1527-1549 nm), each spaced by 2 nm     

Plastic optical fibre with improved transmittance

A low-loss plastic optical fibre has been manufactured employing polystyrene as core material. The minimum transmission loss was 140 dB/km at 670 nm, and intrinsic material loss of polystyrene was estimated to be 105 dB/km.     

DBR-based tunable optical filter

A device structure for implementing a continuously tunable optical filter is described. The proposed filter relies on the creation of a resonant optical cavity between a high-reflectivity mirror and a periodic grating, with a phase control section in between. The filter has only one transmission peak over the entire frequency range, can be tuned in a few nanoseconds, and is suitable for integration with the receiver in a photonic circuit     

High temperature Fabry-Perot probe interrogated with tunable fibre ring laser

A high temperature fibre-optic based probe is described based on a miniature Fabry-Perot with a maximum operating temperature of ~700degC limited by the gold coated fibre transceiver link connecting the optical source to the probe. It was interrogated by a tunable fibre laser which could be linearly or sinusoidally tuned at scanning rates of 2 and 20 kHz, respectively. The transfer function of the system is in the form of channelled spectra rather than the usual interference fringes observed for interferometric sensors. The periodicity of the channelled spectra fringes is governed by the Fabry-Perot free spectral range which is related to the inverse of the probe temperature.     

Electrically tunable singlemode fibre Bragg reflective filter

An electrically tunable singlemode fibre Bragg reflective filter (FBR) is demonstrated for the first time by using a large amount of magnetostrictive material in which the fibre is embedded and side-polished. With a reflection bandwidth of ~1.5 nm, the measured tuning range of the FBR filter is 1.3 nm     

High-power broadly tunable erbium-doped silica fibre laser

A Ti:sapphire laser at 980 nm has been used to pump a grating-tuned erbium-doped silica fibre laser. 540 mW launched pump power produces up to 270 mW tunable output near 1.55 mu m, with more than 250 mW obtainable from 1.52 to 1.57 mu m.<>     

超窄带宽可调光滤波器的研究

为了降低可调光滤波器的带宽,采用双光栅结构和基于微机电系统的反射镜相结合的方法,构建了具有波长连续可调谐的超窄带宽滤波器,并进行了理论分析和实验验证,取得了滤波带宽小于0.4nm的数据。结果表明,双光栅结构的光滤波器具有性能稳定、重复性优良的性能特点,并且很好地满足了带宽需求。这种结构显著降低了可调谐光滤波器的滤波带宽,提高了系统的稳定性。     

Thermally tunable integrated optical ring resonator with poly-Sithermistor

Doped polysilicon is applied as a thermo-optic heating element to temperature tune the ring resonator based on silicon nitride rib waveguides on silicon. The ring diameter is 2 mm allowing a large free spectral range of 26 GHz. For the first time, a poly-Si resistor is used as a thermistor to measure waveguide temperature. The temperature coefficient of the poly-Si thermistor is 9.5×10^-4/°C. The reproducibility of the temperature measurement is 0.3°C. The finesse of the ring resonator is 77. The propagation loss of silicon nitride rib waveguide is 0.5 dB/cm at the wavelength of 1.312 μm. The temperature tuning of the ring resonator and the in situ supervision of the temperature on chip based on the same poly-Si fabrication process may find use especially in optical sensor applications     

Low-loss polarisation-maintaining optical fibre with low crosstalk

A low-loss polarisation-maintaining optical fibre with low crosstalk is presented. The minimum transmission loss is 0.35 dB/km at 1.54 ?m and crosstalk is ?32 dB at 1.56 ?m in a 1 km length. The relative refractive index difference between core and cladding is 0.3%, and the modal birefringence is 2.8 × 10?4.