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1.
Polarization properties of elliptical core non-hexagonal symmetry polymer photonic crystal fibre 总被引:1,自引:0,他引:1 下载免费PDF全文
In this paper, polarization properties and propagation
characteristics of polymer photonic crystal fibres with elliptical
core and non-hexagonal symmetry structure are investigated by using
the full vectorial plane wave method. The results show that the
birefringence of the fibre is induced by asymmetries of both the
cladding and the core. Moreover, by adjusting the non-symmetrical
ratio factor of cladding $\eta$ from 0.4 to 1 in step 0.1, we find
the optimized design parameters of the fibre with high
birefringence and limited polarization mode dispersion, operating in
a single mode regime at an appropriate wavelength range. The range of
wavelength approaches the visible and near-infrared which is
consistent with the communication windows of polymer optical fibres. 相似文献
2.
Based on a full-vector model, a theoretical study on a kind of high birefringence photonic crystal fibre is presented. Due to introducing air holes of two different sizes into the cladding, twofold rotational symmetry was obtained. We demonstrate the possibility of achieving high birefringence that is at least one order of magnitude higher than that of conventional polarization-maintaining fibres. The dependences of modal birefringence, modal field and differential group delay on the structure parameter of the fibres are discussed in detail. The numerical results are in very good agreement with the experimental results in the literature. 相似文献
3.
The highly Ge-doped photosensitive fiber (PSF) has been widely used in the fabrication of fiber Bragg gratings (FBGs). Its birefringence and cladding mode coupling characteristics greatly influence FBG's transmission feature in communication application areas. In this work, a new concept of the PSF is introduced which, along with an optimized birefringence design, a precisely controlled fabrication process, and a cladding mode depressed design, results in a written FBG with -25-dB clad mode-depressed ratio and a polarization mode dispersion value less than 0.045 ps. 相似文献
4.
Using the finite element method, this paper investigates lateral
stress-induced propagation characteristics in a photonic crystal
fibre of hexagonal symmetry. The results of simulation show the
strong stress dependence of effective index of the fundamental
guided mode, phase modal birefringence and confinement loss. It also
finds that the contribution of the geometrical effect that is
related only to deformation of the photonic crystal fibre and the
stress-related contribution to phase modal birefringence and
confinement loss are entirely different. Furthermore,
polarization-dependent stress sensitivity of confinement loss is
proposed in this paper. 相似文献
5.
To obtain the stable operation of erbium-doped fibre laser, the
simple and ideal technology is adopted by use of the erbium doped
polarization maintaining fibre (EDPMF). The design criteria of the
Panda-type EDPMF are presented, which take into account the cutoff
wavelength, mode field diameter, modal birefringence and background
loss. Four groups of optimum structural parameter combinations are
determined in terms of the design criteria. Two kinds of the
Panda-type EDPMFs are selected to be fabricated. The fabrication
process and the parameter control of the Panda-type EDPMFs are
presented in detail. Their refractive index profiles, birefringence
and absorption spectra are experimentally investigated. The
absorption coefficient of the EDPMF, whose core is co-doped with Bi,
Ga, Al and Ge, is about 57.9dB/m at 1.53\mum. Co-doping Bi, Ga
and Al can greatly increase the erbium concentration in the
silica-based fibre. The high birefringence is obtained for the
Panda-type EDPMF. The group birefringence of the EDPMF, whose outer
cladding diameter is 125\mum, is about 4.8\ti10-4. 相似文献
6.
7.
An optical time-domain differentiation scheme is proposed and demonstrated based on the intensive differential group delay in a high birefringence fibre waveguide. Results show that the differentiation waveforms agree well with the mathematically calculated derivatives. Both error and efficiency will increase when the birefringence fibre becomes longer, and the error rises up more quickly while the efficiency approaches to a maximum of ~0.25. By using a 1-m birefringence fibre a lower error of ~0.26% is obtained with an efficiency of 1% for the first-order differentiation of 10-ps Gaussian optical pulses, and the high-order optical differentiation up to 4th order is achieved with an error less than 3%. Due to its compact structure being easy to integrate and cascade into photonic circuits, our scheme has great potential for ultrafast signal processing. 相似文献
8.
A Room-Temperature Multiwavelength Erbium-Doped Fibre Laser by Exploiting Polarization Hole Burning 下载免费PDF全文
Multiwavelength operation of a linear cavity erbium-doped fibre laser (EDFL) is proposed and demonstrated. A 3-dB fibre loop mirror and a high birefringence (HiBi) fibre loop mirror are utilized as the cavity reflectors. By utilizing the wavelength-dependent polarization rotation induced by the HiBi fibre loop mirror and by using a fibre polarizer to control the intracavity polarization state, the polarization states of different wavelengths are diversified. Therefore, the polarization hole burning (PHB) effect has been greatly enhanced and the homogeneous broadening of erbium-doped fibre is suppressed to a large extent. By simply tuning a polarization controller, we experimentally obtained simultaneous lasing of four and five wavelengths with wavelength spacing of ~1.8nm and less than 2nm at room temperature, respectively. The repeated scans show that all of these lasers have good stability. 相似文献
9.
A kind of high birefringence SF6 soft glass photonic crystal fiber (HBSF6-PCF) is proposed. The properties of birefringence, dispersion, nonlinear coefficient and the transmission characteristics are studied by the multipole method and the adaptive split-step Fourier method. The numerical results show that the birefringence and the nonlinear coefficient reach the orders of 10^-2 and 10^-1, respectively. In addition, the HBSF6-PCFs can generate very smooth supercontinuum spectra when illuminated with femtosecond pulsed light of 1064 nm. It is found that up to 800nm spectral width (evaluated at -5dB from the peak) is achieved. Therefore, the advantage of the HBSF6-PCFs is such that a high birefringence, a high nonlinearity and a smooth supercontinuum are perfectly combined in them. 相似文献
10.
Temperature dependence of birefringence in olarization-maintaining photonic crystal fibres 下载免费PDF全文
In this paper,the temperature dependence of birefringence in polarization maintaining photonic crystal fibres(PMPCFs) is investigated theoretically and experimentally.Utilizing the structural parameters of the PM-PCF samples in the experiment,two effects leading to the birefringence variation under different temperatures are analysed,which are the thermal expansion of silica material and the refractive index variation due to the temperature variation.The actual birefringence variation of the PM-PCF is the combination of the two effects,which is in the order of 10-9 K-1 for both fibre samples.Calculation results also show that the influence of refractive index variation is the dominant contribution,which determines the tendency of the fibre birefringence variation with varying temperature.Then,the birefringence beat lengths of the two fibre samples are measured under the temperature,which varies from -40℃ to 80℃.A traditional PANDA-type polarization maintaining fibre(PMF) is also measured in the same way for comparison.The experimental results indicate that the birefringence variation of the PM-PCF due to temperature variation is far smaller than that of the traditional PMF,which agrees with the theoretical analysis.The ultra-low temperature dependence of the birefringence in the PM-PCF has great potential applications in temperature-insensitive fibre interferometers,fibre sensors,and fibre gyroscopes. 相似文献
11.
Photoelectric Hybrid Optical Bistable Device Using Fibre Bragg Gratings with Two Feed Signals 下载免费PDF全文
A photoelectric hybrid optical bistable device (OBD) is investigated by using fibre Bragg gratings as a lightintensity modulator. A new operation with two feed signals is proposed, and with this method the output characteristic of the OBD is remarkably improved. The potential application of such a device in optic stabilizer for fibre laser is also briefly discussed. 相似文献
12.
Mueller-Matrix-Based Differential Rotation Method for Precise Measurement of Fiber Birefringence Vector 下载免费PDF全文
The method of complete polar decomposition for arbitrary Mueller matrixes is introduced to analyze the birefringence vector induced in a fiber, and then based on the Mueller matrix (MM) method, three kinds of computation methods including the absolute, the relative, and the differential rotation methods are proposed and investigated in detail. A computer-controlled measure system is employed to measure the Mueller matrix and birefringence vector for a 2.5-km fiber system with length 5 mm under lateral press in complicated environment with much perturbation. Experimental results show that the differential rotation (DR) method is the optimal approach to achieve fiber birefringence vectors in a large dynamic range of lateral press on fibers in perturbed situations, which reaches the highest linearity of 0.9998 and average deviation below 2.5%. Further analyses demonstrate that the DR method is also available for accurate orientation of lateral press direction and the average deviation is about 1.1°. 相似文献
13.
基于高双折射光子晶体光纤环镜的全光纤平顶梳状滤波器 总被引:1,自引:0,他引:1
A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top output with a high extinction ratio. Compared to filters consisting of the conventional Panda polarization main- taining fibre, filters based on a high birefringence photonic crystal fibre loop mirror have better temperature stability. This kind of filter can be expected to be used widely in Wavelength-division-multiplexing(WDM) systems in the future. 相似文献
14.
A Novel Method to Calculate the Initial Phase Difference between the Two Fibre Arms of Laser Homodyne Iuterferometer 下载免费PDF全文
We suggest a novel method to calculate the initial phase difference between two fibre arms of a laser homodyne interferometer. Put the two fibre arms in a temperature controller, whose short term stability is 0.02° C (measured in an hour), then measure the interference photocurrent and the photocurrents from the two fibre arms at a fixed temperature. With these three photocurrents we can calculate the value of the initial phase difference. We set up a simple laser homodyne interferometer to test the theory. The experimental results are repeatable and the measurement precision is about 0.04°. It is theoretically and experimentally proven that this method is potentially easy and practical. 相似文献
15.
Temperature or strain induced adjustable-chirp characteristics of uniform fibre grating with tapered metal coating 下载免费PDF全文
Temperature and strain characteristics of uniform fibre grating with
tapered metal coatings have been analysed theoretically, by which
adjustable chirp characteristics of such gratings are shown.
Electroplating is adopted to fabricate such gratings, and the tapered
metal coating is obtained by gradually drawing the fibre grating out
of the solution during the process of electroplating. The gradually
changing cross-sectional area of the metal coating is calculated by a
newly suggested numerical method. By combining the theoretical and
numerical simulation analyses, the gratings' characteristics are
given at various temperatures and strains. The results obtained using
such a method are also testified by experiments. 相似文献
16.
Improved high birefringence photonic crystal fibres with dispersion flattened and single mode operation 下载免费PDF全文
A kind of improved high birefringence photonic crystal fibre (PCF) is proposed in this paper. The characteristics of birefringence, dispersion and leakage loss are studied by the multipole method. Numerical results show that the improved PCF possesses the properties of a flat dispersion and single mode operation. Moreover, with the operating wavelength λ = 1.55μm, the modal birefringence increases greatly in comparison with that of the original PCF, and the leakage loss is about 104 times smaller than that of the original PCF because the modification gives rise to the strong confinement of guided modes. It is expected that the improved PCF can be used as high birefringence and dispersion flattened fibres. 相似文献
17.
Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror 下载免费PDF全文
This paper demonstrates a room-temperature multiwavelength
fibre laser with spacing-adjustability and wavelength-tunability.
The nonlinear gain of self-excited stimulated Brillouin scattering
can suppress mode competition induced by homogeneous broadening of
Erbium-doped fibre. With the use of a birefringence fibre loop
filter, the wavelength spacing can be adjusted by changing the
length of the used birefringence fibre, and the lasing wavelengths
can be finely tuned through modifying the filtering profile of the
birefringence filter. Multiwavelength output with spectral spacing
as small as 0.076~nm and a wavelength number of more than 80 has been
successfully produced. 相似文献
18.
Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation 总被引:1,自引:0,他引:1 下载免费PDF全文
We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier (MOPA) configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved. It can be used not only to obtain high power fibre laser array but also in laser space communication. 相似文献
19.
The most general model of elliptical birefringence in an optical fiber is extended to describe a transient Bril-louin interaction including both gain and loss. The effects of elliptical birefringence cause a Brillouin spectral shape distortion, which is detrimental for fiber sensing techniques. The model investigates the effects of bire- fringence and the corresponding evolution of spectral distortion effects along the fiber, and also investigates regimes where this distortion is minimal. 相似文献
20.
Realization of Arbitrary Inverse Unitary Transformation of Single Mode Fibre by Using Three Wave Plates 下载免费PDF全文
We report a method to realize the arbitrary inverse unitary transformation imposed by a single-mode fibre on photon's polarization by the succession of two quarter-wave plates and a half-wave plate. The process of realization is analysed on a Poincar6 sphere due to the fact that unitary transformation does not change the angle formed by polarization state vector. The method is meaningful in quantum communication experiment such as quantum teleportation, in which an unknown arbitrary quantum state should be kept to be unchanged in the case of using a single-mode fibre for time delay.[第一段] 相似文献