共查询到20条相似文献,搜索用时 15 毫秒
1.
Multi-wavelength Brillouin-Erbium fibre laser utilising fibre Fabry-Pérot resonator is presented here. The proposed laser cavity used only a 980 nm laser diode and a coil of Erbium-doped fibre to produce cascaded Brillouin Stokes. The highest number of Stokes up to 43 lines with a spacing of 0.088 nm was obtained experimentally. 相似文献
2.
We introduce the concept of cascaded resonant Raman pumping of fibre lasers. The pump scheme utilises the relatively large intracavity Stokes field that is generated within a Raman fibre laser to excite a lanthanide ion that is doped within the core of the fibre providing the Raman gain. In order to illustrate the general characteristics of the pump method and, to establish the design parameters necessary for the realisation of the pump scheme, calculations from a theoretical model that is used to simulate the generation of laser output from a fibre laser that is resonantly pumped with first Stokes radiation is presented. Specifically, the 2.1 μm output from a Ho3+-doped silica fibre laser that is pumped with 1.15 μm first Stokes radiation is calculated with the use of a relatively simple numerical model. For a launched pump power of 20 W at 1.07 μm, a fibre laser output of 3 W is predicted for a nominal intrinsic loss of 1.5 dB/km at 2.1 μm, however, this low value of the intrinsic loss at 2.1 μm can be significantly relaxed when the length of the Ho3+-doped silica fibre laser resonator is made considerably shorter than the Stokes resonator. 相似文献
3.
An integrated optical coupler used in a fibre interferometry system for on-line surface measurements
In this paper, an integrated optical (IO) coupler produced using the technique of silica-on-silicon was described. A fibre interferometry system using the IO coupler was then developed and its performance was tested. The environmental noise and disturbances in this system were reduced significantly after combining a reference interferometer and an all fibre polarisation scrambler so as to produce good stability and repeatability. Furthermore, the measurement mirror was mounted on a piezoelectric transducer (PZT) and disturbances were introduced in the system in order to simulate on-line surface measurements. Both a commercial fibre and the IO couplers were compared using this method. Better experimental results were achieved when the system using the IO coupler than using the fibre one. 相似文献
4.
A novel technique of producing multiwavelength laser source was described utilising a linear cavity of hybrid Brillouin/Erbium fibre laser (BEFL). Twenty-two stable output lasers with 10.88 GHz line spacing were obtained from this architecture at 1557.5 nm that was at the peak of Erbium gain. The requirement of an internal feedback that is commonly used in a ring configuration to generate cascaded Brillouin Stokes for multiple wavelengths operation was achieved by the proposed linear cavity design. 相似文献
5.
We propose a novel optical bit-pattern recognition employing an Opto-VLSI processor in conjunction with an array of fibre Bragg gratings (FBGs) with different Bragg wavelengths and a coherent-to-incoherent light converter. The FBG array slices the spectrum of the incoherent optical header and provides wavelength-dependent time delays, whereas the Opto-VLSI processor generates wavelength intensity profiles that match specific bit patterns. The recognition of 8-bit optical patterns is experimentally demonstrated at 2.2 Gb/s by showing that the correlator produces an autocorrelation waveform of high peak whenever the input bit pattern matches the wavelength intensity profile. 相似文献
6.
Hongliang Ren Chun Jiang Weisheng Hu Mingyi Gao Jingyuan Wang Hui Wang Jintian He Erjun Liang 《Optics & Laser Technology》2007,39(5):1025-1029
As an important component of scanning near-field optical microscope (SNOM), optical fibre nanoprobe has been applied to many fields extensively. A melt-stretched etching method is proposed to produce optical fibre nanoprobe with low cost. Firstly, optical fibre tip with micrometer-sized diameter is created by the melt-stretched measure. Next, it is dipped into hydrofluoric acid (HF), and a fine optical fibre nanoprobe will be made after a short-time etching. Owing to the taper structure of tip, it can be etched again in acid if a nanoprobe is not constructed when the first etching is completed. In addition, optical fibre nanoprobe is applied to spectral investigation, and the fluorescence spectroscopy of rhodamine B (Rh B) solution is collected by an optical investigation system with a bifurcated fibre. 相似文献
7.
A plastic-clad optical fibre system has been examined as a delivery system of pulsed laser energy for the generation of ultrasound. The onset of significant optical damage caused by the laser has been investigated. By using multimode fibres of 1 m length with 600 μm core size, it was found that laser power densities from the fibre were sufficient to produce ultrasonic waveforms corresponding to both the thermoelastic and plasma generation regimes. Out-of-plane acoustic displacements of >250 pm can be achieved through 2.5 cm thick aluminium test samples, showing that fibre optical delivery systems may be considered in systems using laser-generated ultrasound for non-destructive testing applications. 相似文献
8.
Nonlinear systems with periodic variations of nonlinearity and/or dispersion occur in a variety of physical problems and engineering applications. The mathematical concept of dispersion managed solitons already has made an impact on the development of fibre communications, optical signal processing and laser science. We overview here the field of the dispersion managed solitons starting from mathematical theories of Hamiltonian and dissipative systems and then discuss recent advances in practical implementation of this concept in fibre-optics and lasers. 相似文献
9.
The impact of the drawing process on the stress-induced birefringence in optical fiber is experimentally analyzed. By means of the photoelastic tomographic technique, residual internal stresses are measured in fiber samples drawn under different conditions of temperature, drawing tension and speed. From measured residual stress distributions, the stress-induced birefringence and beatlength are mathematically derived and compared, proving that an effective birefringence reduction can be obtained by a proper choice of drawing parameters. 相似文献
10.
W. Zhang Y. C. Lai J. A. R. Williams C. Lu L. Zhang I. Bennion 《Optics & Laser Technology》2000,32(5):369
A distributed feedback fibre laser is realised with a phase-shifted fibre Bragg grating. Dual-mode operation is obtained by means of linear birefringence for heterodyne generation of optical microwave signal. The two modes, operating in the same cavity produce a beat signal with exceptionally low-phase noise. The linewidth of the resulting microwave signal obtained is less than 1 kHz. 相似文献
11.
B.C. Gibson 《Optics Communications》2007,279(2):303-312
The viability and operation of evanescent field-based optical fibre sensors is largely determined by the fraction of the total supported modal field power in the evanescent field. As this fraction is highly dependent on the refractive index profile of the fibre, one design strategy for fibre sensors is to maximize this field power fraction over the class of all refractive index profiles. This paper documents this design strategy for circular geometry optical fibres, where the goal is to maximize the evanescent field power fraction for a particular mode via the selection of an optimal refractive index profile. The axially symmetric profiles obtained approximate “holey” annular structures, the performance of which can be validated using existing waveguide analysis techniques. 相似文献
12.
Using the pulse-reflection-oscillation method, a high precision optical fibre propagation delay measurement system is made and applied to measure multimode optical patchcords of four different lengths (10, 20, 50 and 100 m). The result shows that the standard deviation is less than 11 ps. 相似文献
13.
We have experimentally studied polarization instabilities in the multi-transverse-mode regime of a vertical-cavity surface-emitting laser subject to polarized optical feedback. A dynamical regime that is similar to the transition from the so called low frequency fluctuation (LFF) to coherence collapse (CC) in the single-transverse-mode VCSEL is found and investigated. The role of higher order transverse modes is to increase the irregularity of the dynamics as shown experimentally and numerically. 相似文献
14.
A mismatched optical coupler with waveguide weighted by the Blackman function is numerically investigated in the demand of short length, C+L-band, and low crosstalk. Utilizing the full factorial design, the structure parameters of coupling waveguide are obtained by beam propagation method. In the condition of crosstalk of −35 dB, the mismatched optical coupler with proper selected waveguide structure parameters is found to have a coupling length of 3.60 mm in the transmission wavelength ranges of C+L-band (1.53-1.61 μm). Obviously, the selection and design of waveguide structure are very important to satisfy the qualities of a mismatched optical coupler for the demand of short length, broad bandwidth, and low crosstalk. 相似文献
15.
Operating characteristics of a Q-switched Nd3+: doped single-mode silica fibre with a mechanical chopper as a Q-switching device are presented. Peak powers as high as 16 W with pulse duration of 146 ns are demonstrated. Self-mode-locking in Nd3+:doped fibre is also reported. An output power of 312 W with a centre pulse duration of 4 ns is observed. 相似文献
16.
Diode laser using narrow bandwidth interference filter at 852 nm and its application in Faraday anomalous dispersion optical filter
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We demonstrate an 852-nm external cavity diode laser(ECDL) system whose wavelength is mainly determined by an interference filter instead of other wavelength selective elements. The Lorentzian linewidth measured by the heterodyne beating between two identical lasers is 28.3 k Hz. Moreover, we test the application of the ECDL in the Faraday atomic filter.Besides saturated absorption spectrum, the transmission spectrum of the Faraday atomic filter at 852 nm is measured by using the ECDL. This interference filter ECDL method can also be extended to other wavelengths and widen the application range of diode laser. 相似文献
17.
We report on the experimental investigation carried out in the polarisation characteristics of femtosecond pulsed and continuous wave beams propagating through a 1×2 fibre coupler. It is demonstrated that the polarisation states of pulsed and continuous wave illumination over the broad wavelength range can be preserved in a conventional fused fibre coupler. Furthermore, the fibre coupler acts as a low-pass spectral filter in the visible wavelength range with a splitting ratio between 99.6/0.4 and 99.7/0.3. The result is of importance for fibre-optic second harmonic generation microscopy which requires the polarisation preservation to extract molecular organization of a sample. 相似文献
18.
The stability and reliability of probe laser is an important factor affecting the inspection of the phase transformation process of Si thin films during excimer laser crystallization using in-situ time-resolved optical measurements. The changes in 2D intensity profile, peak power density, and beam wander of the commonly used helium–neon (He–Ne) and diode laser are investigated experimentally. It is found that the peak power density of He–Ne laser is higher than that of diode laser, while the total power of He–Ne laser is lower than that of diode laser. Although the instability in the peak power density of He–Ne laser will increase with increasing the operation time, the beam stability of He–Ne laser is better than that of diode laser. For long-time operation (>24 h) of optical measurements, the diode laser is a good candidate of probe laser. Conversely, the diode laser is suitable for the short-time operation (<24 h) of optical measurements because the beam-wander is higher than that of He–Ne laser. 相似文献
19.
We describe an interferometric technique for the demodulation of serial fibre Bragg grating sensor arrays, yielding absolute measurement of the individual grating mean wavelengths. The composite beam reflected from the array illuminates a scanning Michelson interferometer but, in contrast to spectral measurement by Fourier Transform Spectroscopy, our technique requires an OPD scan far shorter than the coherence length of the grating reflections. The technique is based on the high-resolution measurement of the phases of the complex analytic signals and of the relationship of these phases to interferometric delay. The analytic signals are derived via the Hilbert transform, allowing frequency domain filtering of individual signals within the signal processing. The technique has yielded a resolution of 0.007 nm for an OPD scan of 1.2 mm. 相似文献
20.
A detailed numerical study of soliton switching in a nonlinear directional coupler with saturating nonlinearity is carried out. All commonly used models have been studied. Relevant physical characteristics for switching have been determined, compared and discussed. 相似文献