Simple structure high isolation multi/demultiplexer

Wavelength division multiplexing (w.d.m.) techniques, which transmit light signals with different wavelengths through a single optical fibre, are required to increase transmission capacity. The letter describes a new type of multi/demultiplexer using an interference filter and a single graded-refractive-index (g.r.i.n.) rod lens. It has a simple structure and a low near-end crosstalk (less than ?50 dB).     

High-performance guided-wave multi/demultiplexer based on novel design using embedded gradient-index waveguides in glass

A guided-wave multi/demultiplexer which comprises low-loss gradient-index ion-exchange waveguides embedded in a glass substrate and optimised interference filters was successfully fabricated. Around ? 1dB insertion losses for demultiplexing and less than 2dB insertion losses for multiplexing with sufficient transmission bandwidth as wide as 66 nm were achieved.     

In-line single-mode wavelength division multiplexer/demultiplexer

A single-mode fibre optic wavelength division multiplexer/demultiplexer at 1.32 ?m and 1.55 ?m, constructed from a fused evanescent wave coupler, is described. This device has an insertion loss of less than 0.05 dB and a wavelength isolation of 16 dB at 1.32 ?m and 18 dB at 1.55 ?m.     

High-isolation single-mode wavelength-division multiplexer/demultiplexer

A single-mode fibre-optic wavelength-division multiplexer/demultiplexer with excellent isolation is reported. The device utilises a fused biconical structure similar to that of 3 dB couplers and exhibits an insertion loss of 0.04 dB and a wavelength isolation of 43 dB at 1.300 ?m and 30 dB at 1.523 ?m.     

Fused taper/filter hybrid single-mode wavelength divisionmulti/demultiplexer

A low loss and low crosstalk single-mode wavelength division multi/demultiplexer was successfully fabricated by embedding an interference filter in each output arm of a fused taper coupler. The insertion loss was around 1.5 dB at the wavelengths of 1.3 μm and 1.55 μm, and both near-end and far-end crosstalks were less than -50 dB     

Coupler type multi/demultiplexer composed of different parameter fibres

A new type of coupler, a 1.31/1.55 mu m wavelength multi/demultiplexer composed of different parameter fibres, has been fabricated. The maximum coupling ratio of 97% with an excess loss of 0.6 dB was obtained at 1.3 mu m wavelength by using Delta =0.3 and 1.8% step index core single-mode fibres.<>     

一种基于三芯光纤的模式复用器/解复用器的设计

提出了一种基于三芯光纤的模式复用器/解复用器,三个纤芯包括两个相同的单模纤芯和一个少模纤芯,在少模纤芯中写入长周期光纤光栅以实现单模纤芯中LP01模与少模纤芯中LP11模间的转换。同时从两个单模纤芯输入LP01模,能激发少模纤芯中两个简并的LP11,a模和LP11,b模。采用光束传播法分析了该模式复用器/解复用器的耦合特性及串扰。数值模拟结果显示,若以少模纤芯中LP11模输出能量大于-1dB的波长范围作为该模式复用器/解复用器的工作带宽,则能够达到23nm,并且少模纤芯中生成的其他模式的输出能量皆比LP11模的输出能量小-21dB以上。该模式复用器/解复用器能够实现对少模光纤的模式复用与解复用,并具有极低的串扰。     

Y-branch wavelength multi/demultiplexer for gamma =1.30 and 1.55 mu m

A Y-branch wavelength multi/demultiplexer for optical WDM communication systems has been investigated. An Al/sub 2/O/sub 3/ strip is loaded on one of the ion-exchanged arms formed in soda-lime glass. The wavelength separation was demonstrated with extinction ratios of 5.3 and 5.7 dB at 1.30 and 1.55 mu m, respectively.<>     

A TM Y-branch wavelength multi/demultiplexer by K+ andAg+ ion-exchange for λ=1.31 and 1.55 μm

A Y-branch multi/demultiplexer by K⁺ and Ag⁺ ion-exchange was optimally designed, using the 2-D beam propagation method (BPM) and successfully fabricated for λ=1.31 and 1.55 μm. The measured extinction ratios of our preliminary devices are about 20 dB     

硅基竖直耦合三环谐振波分复用器的特性

对1×N信道硅基竖直耦合三环谐振波分复用器的传输特性进行了分析,给出了光学传递函数的公式.在中心波长1550.918nm、波长间隔1.6nm的情况下,对其振幅耦合比率、波谱响应、分光光谱、插入损耗、信道间的串扰进行了数值模拟.计算结果表明,该器件具有以下良好性能:若取小环与信道间的振幅耦合比率为0.27,小环与大环间的振幅耦合比率为0.06,该器件具有箱形波谱响应,输出光谱中的次峰值已被抑制到-25dB,谐振峰平坦且陡峭,3dB带宽约为0.28nm,每条输出信道的插入损耗及串扰较小,插入损耗小于0.71dB,串扰可降至-53dB以下.     

Optical demultiplexer using concave grating in 0.7?0.9 ?m wavelength region

Experimental results of a demultiplexer using an aberration corrected concave grating for an optical system are described. The demultiplexer has 10 channels and a wavelength spacing of 20 mm from 0.7 to 0.9 ?m wavelengths. Insertion losses and crosstalk were less than 2.5 dB and -30 dB, respectively, for all channels.     

Multireflection optical multi/demultiplexer using interference filters

A multireflection multi/demultiplexer using interference filters is proposed. Light waves of different wavelengths are combined or separated while they propagate between two filter arrays. The insertion loss of the 6-channel demultiplexer was around 1dB.     

Wavelength-division multi/demultiplexer utilizing optically activecrystals

A wavelength-division multi/demultiplexer (W-MUX/DEMUX) utilizing optically active crystals is proposed and studied. It is shown that using two or more optically active crystals having different rotary powers and dispersions is effective for providing design freedom and for easy assembly of the W-MUX/DEMUX. A design for a two-wavelength W-MUX/DEMUX is also discussed. Based on this design, a W-MUX/DEMUX that multiplexes or demultiplexes light with wavelengths of 0.8 and 1.1 μm was fabricated. The insertion losses are 1.6 and 3.1 dB at wavelengths of 0.8 and 1.1 μm, respectively. Crosstalk attenuation of 13 dB or more is obtained at these wavelengths     

20-Channel micro-optic grating demultiplexer for 1.1?1.6 ?m band using a small focusing parameter graded-index rod lens

A 20-channel micro-optic grating demultiplexer with a single-mode input fibre has been developed for 1.1?1.6 ?m band using a newly developed graded-index (Selfoc) rod lens with a small focusing parameter and an Si-etched reflection grating. Insertion losses were 1.9 to 3.5 dB. Isolation between adjacent channels was less than ?20 dB.     

Crosstalk reduction in N×N WDM multi/demultiplexers bycascading small arrayed waveguide gratings (AWG's)

This paper shows a new scheme which improves the crosstalk performance of large optical multi/demultiplexers, a key component in wavelength division multiplexing (WDM) systems. This scheme uses arrayed waveguide gratings (AWG's) of various sizes and requires no additional equipment. It is well known that a large multi/demultiplexer can be constructed by cascading small multi/demultiplexers. We have studied the impact of the number and size of AWG stages on crosstalk performance. This paper proves that to obtain a multistage multi/demultiplexer with minimum crosstalk, the total channel number of each AWG stage must be minimized. For example, cascading 10-channel AWG's and 11-channel AWG's improves the crosstalk performance of a 110-channel multi/demultiplexer by about 7.5 dB. Furthermore, the crosstalk performance degradation due to fabrication error is theoretically investigated taking channel bandwidth into account. Optimum design parameters of multistage AWG's are introduced: When the AWG suppression ratio is 30 dB and the ratio of channel bandwidth to channel spacing is about 0.24, the degradation in crosstalk performance due to fabrication error is minimized. The tradeoff between the crosstalk performance and the efficiency in terms of hardware and wavelength are also discussed. It is discovered that this simple scheme can yield a crosstalk-free WDM router. Crosstalk reduction obtained by this scheme allows the realization of flexible multiwavelength networks based on wavelength routing     

InGaAsP Y-branch grating demultiplexer

We report on the fabrication of a passive Y-branch wavelength-division demultiplexer with InGaAsP/InP rib waveguides. The wavelength-selective elements are Bragg reflection gratings on top of the two output ribs of the branch. A channel spacing of 13.5 nm in the 1.5?m region and a crosstalk attenuation of more than 18 dB for TE-polarised light were achieved.     

CWDM multi/demultiplexer consisting of stacked dielectric interference filters and off-axis diffractive lenses

A compact coarse wavelength-division multi/demultiplexer based on a stack of dielectric interference filters and an array of off-axis diffractive lenses is reported. The prototype optical system was packaged in the volume of 6.4 (width) /spl times/ 2.5 (height) /spl times/ 8.2 mm (depth). The optical system is interfaced via a multichannel connector with single-mode fiber ribbons. Optical insertion losses are better than 5 dB. The worst channel crosstalk was -19 dB.     

Silica-based integrated optic Mach-Zehnder multi/demultiplexerfamily with channel spacing of 0.01-250 nm

A Mach-Zehnder (MZ) interferometer design is presented for application to wavelength-division multiplexed/frequency division multiplexed (WDM/FDM) systems. A variety of integrated-optic devices with low loss and low crosstalk, using silica-based waveguides, are demonstrated. MZ interferometers operate as multi/demultiplexers or frequency-selection switches. The channel spacing is determined by the waveguide arm length difference, and a spacing range of 1 GHz to 36 THz, corresponding to a wavelength spacing of 0.008-250 nm, is achieved. The devices for the WDM region have low fiber-to-fiber loss of 0.5 dB, and the devices for the FDM region have higher losses of 2-5 dB. Crosstalk of less than -15 dB was obtained for all the devices. A 5-GHz-spaced 16-channel frequency selection switch and a 10-GHz-spaced eight-channel multi/demultiplexer were also fabricated with a total loss of 5 dB and total crosstalk of -10 dB or less     

Broad-passband-width optical filter for multi/demultiplexer using a diffraction grating and a retroreflector prism

The letter describes the experimental results of a novel optical filter for a multi/demultiplexer using a diffraction grating and a retroreflector prism. A broader passband width, which is proportional to the difference between the prism base length and the input fibre core diameter, is obtained. The minimum insertion loss is 2.2 dB.     

Wavelength demultiplexing using bends in a single-mode opticalfiber

A method of wavelength demultiplexing is developed that makes use of the wavelength and bend-radius dependence of the pure bend loss at single radius bends in a single-mode fiber. The light leaving the fiber at a bend forms one output of the demultiplexer. Equations are derived that predict the bend radii for the most-efficient operation of the demultiplexer and the power extracted from the fiber at each wavelength. The demultiplexer operates over the wavelength range corresponding to V numbers from 2.4 to 1.6. A two-wavelength demultiplexer formed from 90° bends is constructed and tested. Collection efficiencies of 70% and insertion losses of less than 2 dB are shown to be possible. Crosstalk isolation in excess of 40 dB can be achieved with the aid of optical wavelength filters. The performance of a three-wavelength demultiplexer is also considered