共查询到20条相似文献,搜索用时 15 毫秒
1.
An all-fiber tunable bandpass filter (TBPF) based on cascaded twin-core fiber (TCF) is theoretically analyzed and experimentally demonstrated. The spectrum of this proposed TBPF can be easily adjusted by bending, twisting, stretching, or changing the length of TCF to achieve the required filter parameters. In the example of a TBPF fabricated with TCF, the center wavelength can be tuned from 1540.8 to 1557.8 nm, while the full width at half-maximum bandwidth of the filter maintains around 6.5 nm. 相似文献
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非对称光纤反射镜的可调谐光纤激光器 总被引:1,自引:0,他引:1
提出一种非对称窄带光纤环形反射镜结构的可调谐掺铒光纤激光器。980nm泵浦光对掺铒有源光纤进行抽运,高双折射光纤、偏振控制器(PC)和光纤耦合器构成窄带光纤反射镜,窄带光纤反射镜和普通光纤反射镜组成激光谐振腔,利用窄带光纤反射镜工作带宽纳米量级的特性得到单纵模激光。调整偏振控制器改变反射镜对不同波长的反射率,实现可变波长的激光输出。实验表明,该激光器的工作带宽为8nm,120mW泵浦光条件下最大输出功率为4mW,3dB带宽(脉冲的半高宽度)小于0.2nm,边模抑制比为20dB以上,在1527nm~1535nm的波长范围内观察到稳定激光输出。 相似文献
3.
Refractive index sensing based on Mach-Zehnder interferometer formed by three cascaded single-mode fiber tapers 总被引:1,自引:0,他引:1
We report a highly sensitive refractive index (RI) sensor based on three cascaded single-mode fiber tapers, in which a weak taper is sandwiched between the two tapers to improve the sensitivity of the sensor. Experimental results show that the sensitivity of the device is 0.286 nm for a 0.01 RI change, which is about four times higher than that of the normal two-cascaded-taper-based Mach-Zehnder interferometer. In addition, the sensitivity of the device could be enhanced by tapering a longer and thinner middle weak taper. Such kinds of low-cost and highly sensitive fiber-optic RI sensors would find applications in chemical or biochemical sensing fields. 相似文献
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A temperature-controlled, continuously and linearly tunable multiwavelength filter based on cascaded long period fiber gratings
has been realized. For the first time, a tunable wavelength range of 2.1 nm has been achieved with a temperature variation
of 62°C and a regression coefficient of 0.997. The experimental results are in good agreement with the theory. 相似文献
7.
We report a detailed investigation on the effect of semiconductor laser phase noise on the achievable frequency stability when locked to a Mach-Zehnder interferometer fringe. We show that the modulation-demodulation operation produces in the presence of laser phase noise two kinds of excess noise, which could be much above the shot noise limit, namely: conversion noise (PM-to-AM) and intermodulation noise. We show that in typical stabilization conditions, the frequency stability of the locked laser is limited by the intermodulation excess noise. This effect, reported initially in the microwave domain, can be considerably reduced by a convenient choice of the modulation frequency. To our knowledge, this is the first time such a phenomenon is reported in the optical domain. 相似文献
8.
We describe the design, fabrication, and performance of a fiber Bragg grating-based tunable optic filter. The filter, driven by two piezostacks, consists of a flexural hinge structure for displacement magnification and a fiber-ferrule assembly for axial compression of the fiber grating. Finite-element analysis was used to design the mechanical structure to achieve the required displacement magnification and the force for grating compression. A passive thermal compensation design was implemented to reduce thermal-induced wavelength drift. A feedback control system with a linear variable differential transformer was employed to control the displacement for accurate wavelength tuning and fine-tuning resolution. This tunable filter has achieved a closed-loop switching time of 17.3 ms, and a passive thermal compensation that reduced the thermal drift of the Bragg wavelength to 1.5 pm/C. The flexural-hinge structure that offers negligible backlash, noise-free motion, no need of lubricants, and no wear ensures its long-term reliability. 相似文献
9.
A high-performance multiple-channel erbium-doped fiber laser (EDFL) is proposed and experimentally demonstrated, using graphene-polymer nanocomposite as a multiwavelength equalizer and an asymmetric two-stage polarization-maintaining fiber (PMF) Sagnac loop as a flexible comb filter. At first, the filtering characteristics of the PMF Sagnac loop filter (SLF) are investigated. Both theoretical and experimental results show that it can provide a flexibly switchable and tunable comblike filtering. Then, the two-stage PMF SLF is inserted into a graphene-assisted EDFL cavity for generating multiwavelength oscillation. The extreme-high third-order optical nonlinearity of graphene is exploited to suppress the mode competition of the EDFL, and a stable multiple-channel lasing is observed. By carefully adjusting the polarization controllers in the two-stage PMF SLF, not only can the lasing-line number per channel be switchable between single and multiple wavelengths, but also the wavelength spacing in the triple-wavelength condition can be tunable. In the case of triple wavelengths per channel, up to 12 wavelengths with four channels stable oscillations can be achieved. The multiple-channel EDFL can keep a high extinction ratio of >40 dB and a narrow linewidth of <0.01 nm. 相似文献
10.
The nonlinear index of refraction in a resonant region has been determined by the use of a fiber-based Mach--Zehnder interferometer to measure the temporal fringe shift between two signals. The measurement technique is direct and does not require additional amplitude information for the extraction of the nonlinear index of refraction. This technique has been used to measure the temporal response of an InGaAsP semiconductor optical amplifier at 1.313 μm. 相似文献
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This paper describes a new optoelectronic device—an optical transistor that provides power amplification of output visible
radiation. The optical transistor is structurally based on a metallized semiconductor plate with a microchannel gap in the
form of a planar Mach-Zehnder interferometer. A device of the light-light type is controlled by modulating the refractive
index in one arm of the interferometer.
Pis’ma Zh. Tekh. Fiz. 24, 17–21 (January 26, 1998) 相似文献
14.
Ye C 《Applied optics》2006,45(6):1162-1168
The optical arrangement of a spectral filter without an intermediate polarizer that was developed based on optical rotatory dispersion and test measurement results are presented and described. The filter uses three dispersive polarization rotators as the key elements in combination with two additional quarter-wave retarders, and it is wavelength tunable with a spectral transmission equivalent to that of a standard Lyot two-stage filter. 相似文献
15.
Pump efficiency improvement of a C-band tunable fiber laser using optical circulator and tunable fiber gratings 总被引:1,自引:0,他引:1
We propose and demonstrate a tunable fiber laser based on an optical circulator (OC) and two tunable fiber Bragg gratings (TFBGs). The OC acts as a pump power router to improve the pumping efficiency, and a 4% increase in overall conversion efficiency has been observed. The combined tuning spectra range of two TFBGs could cover the entire C-band spectrum from 1530 to 1560 nm. Stable laser output power above 10 dBm is obtained using 1.9 m of erbium-doped fiber and TFBGs with 50% reflectivity. With power equalization by using variable optical attenuators, the power variation is less than 0.1 dB in the whole C band with narrow linewidth of 0.05 nm. A signal-to-noise ratio of 60 dB and a continuous tuning resolution of 0.5 nm have been achieved. The TFBG-based tunable fiber laser can be a promising light source for WDM transmission and fiber sensor applications. 相似文献
16.
A phase difference equation is obtained describing the interference pattern of the initial tuning of a Mach-Zehnder interferometer
on the basis of simulating the mutual orientation of wave fronts. The effect of parameters on this tuning is analyzed. A procedure
is suggested for computing interferograms for any initial tuning.
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Translated from Izmeritel’naya Tekhnika, No. 9, pp. 30–33, September, 2006. 相似文献
17.
A spectrometer has been constructed to detect the radiation emitted by thermally excited samples in the near-infrared spectral region extending from 1500 to 3000 nm. The instrument employs an acousto-optical tunable filter (AOTF) made of TeO2 and attains maximum sensitivity by making effective use of the two diffracted beams produced by the anisotropic AOTF. The full exploitation of the transmitted power of the monochromatic beams is reported for the first time and became possible because the detector does not saturate when employed for the acquisition of the weak emission signal in the NIR region, even when exposed to the total (nondiffracted) beam. Thus, modulation and lock-in-based detection can be employed to find the intensity of the diffracted beams superimposed on the nondiffracted beam. The resolution is slighted degraded in view of the small (approximately 10 nm) difference in the wavelength diffracted in the ordinary and extraordinary beams. The instrument has been evaluated in terms of signal-to-noise ratio, effect of sample thickness, and excitation temperature and for its potential in analytical applications in monitoring high-temperature kinetics, for qualitative identification of inorganic solids, for use with a closed cell to obtain spectra of species that evaporate at the temperatures (> 150 degrees C) necessary for sample excitation, and for quantitative purposes in the determination of soybean oil content in olive oil. The feasibility of near-infrared emission spectroscopy has been demonstrated together with some of its advantages over mid-infrared emission spectroscopy, such as greater tolerance to sample thickness, suitable signal-to-noise, and its use in the investigation of kinetic phenomena and phase transitions at high temperatures. 相似文献
18.
We describe a novel optical acoustic detector based on a bias-controlled fiber Fabry-Perot interferometer. The detector has a broad bandwidth from 10 Mhz to a few gigahertz and higher sensitivity than conventional systems, which are useful for noncontact characterization of microsamples based on laser ultrasound. 相似文献
19.
The operation of a quasi-optical polarization ring interferometer (PRI) performing the function of a diplexer, bandpass filter, and band-stop filter is demonstrated for the first time. It is shown that the beam focusing losses in this interferometer can be reduced using spherical low-permittivity lenses. The results of measurements of the transmission characteristics of a PRI prototype in a 3-mm wavelength range are presented. 相似文献
20.
A magneto-optical bandpass filter composed of a set of Faraday rotators with polarizers inserted between them is proposed. A material analysis for the construction of the filter is performed, and the behavior of the filter is investigated for the most promising magneto-optical materials. It is shown that bandwidths in the range of a few nanometers to tens of nanometers may be achieved depending on the material used in the filter construction 相似文献