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1.
The first experimental Rayleigh backscatter measurements in a passively modelocked fibre ring laser are reported. The Rayleigh backscatter data were used to identify and estimate splice losses as well as the back reflection of the intracavity optical isolator.<> 相似文献
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A distributed feedback laser diode (DFB-LD) module for single-mode fiber coupling is described in the 1.5-μm wavelength region. An optical isolator is constructed in the two lens coupling circuit to stabilize the DFB-LD characteristics. It consists of a DFB-LD as a polarizer, a yttrium iron garnet (YIG) plate and an analyzer. Coupling characteristics and attainable isolation of the proposed circuit have been studied theoretically and experimentally. The effect of reflected light on the DFB-LD characteristics such as relative intensity noise (RIN) and oscillation spectrum has been experimentally investigated taking into account the polarization of the reflected light. It has been clarified that the DFB-LD can function as an effective polarizer with an extinction ratio of more than 20 dB. The DFB-LD module was successfully fabricated to have stable spectrum characteristics and to sufficiently suppress the noise caused by reflections. It has been confirmed by a long haul transmission experiment that this module is applicable to large capacity optical fiber transmission systems. 相似文献
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A new Faraday rotator using a thick garnet film grown by liquid-phase epitaxy (LPE) has been proposed and film growth technology for the rotator has been investigated. The new Faraday rotator had good features of very low cost and small size, due to high productivity of the LPE-grown film and low magnetic saturation field, respectively. By using the new Faraday rotator, an optical isolator and magnetooptic switch for single-mode fiber systems have been developed. The optical isolator featured 0.8-dB insertion loss and 25-dB isolation at 1.3-μm wavelength. The magneto-optic 1 × 2 switch was independent of light polarization and featured 1.3-1.7-dB insertion loss, -25-dB crosstalk, and 30-μs switching time at 1.3-μm wavelength. Minimum switching voltage was ±5 V. Magneto-optic devices using the new Faraday rotator is practical for use in1.2-1.7-mu m wavelength fiber-optic systems, because of good optical properties, compactness, and low cost. 相似文献
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Broadband visible fibre light sources are a promising candidate for many applications, such as fluorescence microscopy, precision interferometry and visible optics testing. These applications require an output greater than a few milliwatts, but the low efficiency of an upconversion fibre ASE light source limits its optical output power to less than 5 mW. To improve the efficiency, co-doping with an active dopant (e.g. Yb/sup 3+/) was used to serve as a pump sensitiser. Recently, the GaN blue laser diode (LD) has been considered as a next-generation pumping source since Weichmann et al. built and demonstrated the use of a 635 nm fibre laser pumped by a GaN LD [1]. However, the fibre output spectra of the amplified spontaneous emission (ASE) and the emission intensity of both a PDF and a PYDF pumped by a GaN blue LD have not been reported. 相似文献
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A guided wave optical isolator using a four layered leaky yttrium iron garnet (YIG) waveguide with a YIG guiding layer is proposed and analyzed through a transfer matrix formulation. The dependence of isolation characteristics on different waveguide parameters are discussed. It is shown that for four layered structures an isolation ratio of about 24 dB can be achieved with YIG films having large gyrotropy. It is also shown that by replacing the single guiding YIG film with multilayers of YIG with compensated walls and proper permittivity, high isolation ratio can be achieved even with currently available YIG films having low gyrotropy 相似文献
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An optical isolator for use at 1.32 ?m has been fabricated using standard communication-grade single-mode fibre as an optical rotator fitted with high-birefringence fibre pigtails containing an in-line tapered fibre polariser. A novel adjustment procedure ensures isolation levels are limited only by the polariser extinction ratio. Isolation levels in excess of 21 dB have been recorded with an insertion loss of less than 3 dB. 相似文献
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A fiber-embedded optical isolator with a low forward loss has been developed. The isolator consists of thermally diffused expanded core fibers, laminated polarizers, and a Faraday rotation garnet. Backward and forward losses at 1.3 μm wavelength are 44.0 and 0.9 dB, respectively. The isolator has a minute size, and its alignment is simple 相似文献
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A fibre-embedded optical isolator without a lens element is proposed and fabricated. The isolator consists of beam-expanding fibres, laminated polarisers and a Faraday rotation garnet. Backward and forward losses at 1.3 mu m wavelength are 36.9 and 1.6 dB, respectively.<> 相似文献
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讨论了一种用于DWDM系统中的光开关、偏振无关隔离器等单元器件中的微小薄膜型偏振分束器制造的关键技术.光学膜层采用数学多重优化设计方法;采用Monte Carlo允差分析原理分析膜层的容差,以便选择更易制备的膜系;计算膜层的Macleod极值灵敏度,得到所选膜系各个膜层的误差要求;模拟光学监控过程,以制定相应的膜厚监控策略.设计了实用的棱镜胶合装置,得到了较高技术指标的PBS棱镜.结果表明,棱镜的光学冷加工,是器件制造的基础;光学薄膜的设计与制备是器件制造的关键,也是难点;棱镜的胶合是器件不可忽视的环节. 相似文献
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An optical isolator for laser-to-single-mode fiber coupling is discussed. The coupling unit consists of a confocal two-lens system with a spherical glass lens and a planoconvex lens which is made of yttrium iron garnet (YIG). To minimize the number of elements, the YIG lens is used as a Faraday rotator as well as a coupling lens. Nevertheless, the planoconvex YIG lens satisfies the requirements of high coupling efficiency, high isolation, and low optical feedback from the Faraday rotator. The arrangement is theoretically and experimentally investigated. At a coupling efficiency of 34%, the total optical feedback into the laser diode was measured to be about -60 dB 相似文献
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Zhuromskyy O. Dotsch H. Lohmeyer M. Wilkens L. Hertel P. 《Lightwave Technology, Journal of》2001,19(2):214-221
Magnetooptical waveguides having nonreciprocal phase shift for both TE and TM modes can be prepared by properly adjusting the spatial variation of the Faraday rotation. Such waveguides are attractive to realize optical isolators. We investigate four concepts of magnetooptical waveguides which yield equal nonreciprocal phase shifts for the fundamental TE and TM modes. A polarization-independent Mach-Zehnder-type integrated optical isolator is presented. All the calculations are performed using material parameters typical for garnet films 相似文献
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The coupling efficiency between the distributed feedback-laser diode (DFB-LD) chip is presented and the single-mode fiber is as high as -5.7 dB (27%) including the insertion loss of the isolator. The spectral linewidth measurement using the self-delayed heterodyne method shows 26 MHz under the condition of IF=I th+50 mA. No changes in the DFB-LD chip properties are observed after packaging. The comparison to another DFB-LD module with a 30-dB isolator confirms the immunity of the spectrum against -14-dB Fresnel reflection. The results show that the DFB-LD module is sufficiently stable to be applied to the coherent lightwave transmission systems 相似文献
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Taga H. Yamamoto S. Mochizuki K. Wakabayashi H. 《Photonics Technology Letters, IEEE》1990,2(4):279-281
The effect of optical back-reflection on the bit-error-rate performance of a semiconductor laser amplifier repeater system is evaluated at 565 Mb/s. It is found that the degradation of the back-reflection is mainly caused by multiple reflection in the amplifier and depends on the internal gain of the optical amplifier and the reflectivity of the reflection points. It is concluded that in optical amplifier repeater systems with large gain, an optical isolator should be used to reduce the back-reflection penalty 相似文献
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We present first monolithic integration of a waveguide optical isolator with a distributed feedback laser diode (DFB LD) in the 1.5-mum wavelength range. The integrated devices are composed of 0.25-mm-long index-coupled DFB LDs and 0.75-mm-long semiconductor active waveguide optical isolators. The semiconductor active waveguide optical isolators are based on the nonreciprocal loss in the semiconductor optical amplifier (SOA) waveguides with ferromagnetic metals (Fe). The fabrication process consists of two steps of metal-organic vapor phase epitaxy to grow the DFB LD/SOA layer structures, one dry-etching process for the waveguide stripe formation, and three steps of electron-beam evaporation for the electrodes and ferromagnetic metals deposition. They showed single-mode emission at 1543.8nm and 4-dB optical isolation under a magnetic field of 0.1 T. 相似文献
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《Microwave Theory and Techniques》1982,30(6):922-925
The characteristics of an optical nonreciprocal phase shifter, with which optical circulators can be constructed, are investigated. We have measured the nonreciprocal phase shift of an appropriately magnetized yttrium iron garnet (YIG) thin film and thus confirmed experimentally that an AIR/YIG/GGG structure can function as an optical nonreciprocal phase shifter. 相似文献