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1.
Distributed optical passive star couplers   总被引:1,自引:0,他引:1  
A technique is presented by which a single centralized passive star coupler in an optical star network is replaced by a distributed one. This is done by partitioning the star coupler into numerous pieces and placing them at the network nodes. Such a placement results in a great saving in the number of fibers required to build the star network. In addition to this saving, the problems associated with constructing a large single N*N star coupler are bypassed.<>  相似文献   

2.
A practical configuration for an amplified distributed reflective N-star coupler using 2×2 3-dB fiber couplers and minimum numbers of erbium-doped fibers, pump lasers, and standard fibers is presented. The constitution and characteristics of this coupler are investigated. Besides a tremendous amount of saving of the required standard fibers, this distributed coupler is more efficient, more reliable, more flexible for future expansion, and more cost-effective for application in optical networks  相似文献   

3.
Reflective single-mode fiber-optic passive star couplers   总被引:2,自引:0,他引:2  
Architecture arrangements for constructing reflective single-mode fiber-optic passive star couplers for high-speed optical local-area networks using simple components, e.g. 3-dB couplers and mirrors, are presented. Besides the savings of fibers, the number of components needed to construct a reflective star is shown to be half of that needed for an equivalent transmissive star. To avoid unpredictable interference effects, only structures that are free of multipaths are considered  相似文献   

4.
It is shown that it is possible to compensate for the approximately 17 dB splitting and excess loss of a 19*19 integrated star coupler with erbium-doped fibers (EDFs) connected to the output channels. The amplifier fibers are pumped to near-quantum-limited noise performance using only one laser source at 0.98 mu m, which is connected to one of the input ports and is distributed to the EDFs through the star itself. The integrated star coupler's near-wavelength-independent performance is able to transmit both the pump light at 0.98 mu m and the signal at 1.55 mu m with a loss differential on the order of only 1 dB.<>  相似文献   

5.
A technique for constructing an efficient N×N star coupler with large N at optical frequencies is described. The coupler is realized in free space using two arrays, each connected to N single-mode fibers. The highest efficiencies are obtained using a planar arrangement of two linear arrays separated by a dielectric slab serving as free-space region. The coupler is suitable for mass production in integrated form, with efficiencies exceeding 35%  相似文献   

6.
Biconically tapered fibre-optic star couplers with up to 100 fibre channels are reported which have excess insertion losses as low as ?0.56 dB and normalised standard deviations of output poers as low as 4.4%  相似文献   

7.
The light-splitting properties of several commercial 8 × 8 transmission- type fiber optic star couplers were investigated for use under abnormal launch conditions. A severe modal selection process was observed. The results of this selection process were first observed in the variation of the throughput for each output fiber depending upon the input fiber used. Subsequently the effect on the emitted radiative profile was measured under a variety of launch conditions. Modal selection was maximized when the launch into the coupler underfilled the input fibers of the coupler, and the effect was minimized when the input was overfilled.  相似文献   

8.
Hermes  T. 《Electronics letters》1991,27(23):2136-2138
A new reflective-type singlemode fibre-optic passive star coupler is described. For this new type of coupler, power entering any one of the ports is divided to all ports except the input port, and thus the optical signal is prevented from returning to its own source.<>  相似文献   

9.
A broadband optical waveguide star coupler with asymmetric directional couplers is proposed. A coupling or splitting ratio of the coupler is flattened with respect to wavelength by choosing appropriate values for Δβ and complete power transfer length. The wavelength characteristics of uniform and alternating Δ&thetas;b directional couplers are investigated, and their broadband operation is shown theoretically. To demonstrate the feasibility of the new proposal, 8×8 star couplers composed of such asymmetric directional couplers are fabricated by using high-silica waveguides on a silicon chip. A star coupler composed of asymmetric directional couplers exhibited 2-dB loss variation in the wavelength range of 1.3-1.55 μm, and this value was almost one fourth of that of a star coupler composed of symmetric directional couplers  相似文献   

10.
We propose a new loss reduction method in star couplers employing UV-written tapers that replace the free propagation region in the conventional star couplers and apply them to an arrayed waveguide grating (AWG) device. The insertion loss of the new AWG device can be reduced to 0.31 dB, which is about 0.7 dB lower than that of the AWG without UV-written tapered waveguides  相似文献   

11.
This paper describes a comparison of three types of 8×8 multimode star couplers made in polymeric multimode waveguides. Their geometry was designed with a ray tracing tool, measurements show low loss for all designs, but a symmetrical design, based on a tree of Y-junctions yields the best uniformity  相似文献   

12.
An N*N optical multiplexer using a planar arrangement of two star couplers   总被引:7,自引:0,他引:7  
The author describes the design of an integrated N*N multiplexer capable of simultaneously multiplexing and demultiplexing a large number (up to about 50) of input and output wavelength channels. The multiplexer is a generalization of the 2*2 Mach-Zehnder multiplexer. It consists of two N*M star couplers connected by M paths of unequal length. Aberrations caused by mutual coupling in the waveguide arrays are minimized by a correction scheme that causes each star coupler to accurately perform a Fourier transformation. The multiplexer should be useful as a wavelength routing device for long haul and local area networks.<>  相似文献   

13.
A simple and accurate method is presented for studying the coupling characteristics of 3D diffused channel waveguide directional couplers. The method is based on the scalar variational principle and differs from other methods as it does not require any assumption for the functional form of the trial field. The authors also propose an equivalent 2D directional coupler that also gives accurate results and, hence, saves considerable computational time, Comparison with experimental and other theoretical results is also presented  相似文献   

14.
In this letter, we report the static performance of multiwavelength DFB laser arrays with integrated star couplers and optical amplifiers built for the reconfigurable optical network testbed. By the use of wavelength redundancy and proximity effect, wavelength deviations of /spl plusmn/0.2 nm or less from the designated eight-wavelength comb have been achieved with high yield. Simultaneous operation of eight wavelengths has also been demonstrated. In spite of the inherent splitting loss of 13 dB, high output powers of about -13 dBm and 0 dBm per wavelength have been measured into a single-mode fiber without and with on-chip optical amplification, respectively.  相似文献   

15.
Someda  C.C. 《Electronics letters》1968,4(26):580-581
A proof is provided of the fact that the formulas for the coupling due to a small hole, obtained by Bethe, correctly apply even to structures which do not exhibit the symmetry, in the plane of the hole, postulated by Bathe.  相似文献   

16.
An asymmetric multimode coupler consists of two dissimilar multimode fibers. A simple theoretical analysis of asymmetric multimode couplers that will enable couplers to be designed with specific performance parameters is presented. The theoretical predictions are compared with the measured behavior of specially fabricated couplers. A novel technique to determine the performance of a linear bus of identical asymmetric couplers from measurements on a single coupler is introduced  相似文献   

17.
Love  J.D. Hall  M. 《Electronics letters》1985,21(12):519-521
A simple mathematical model of long tapered couplers shows that the modulation of the output power due to polarisation has a period which varies inversely with the square of wavelength. This prediction is in agreement with experimental measurements.  相似文献   

18.
Three-guide optical couplers consisting of three 4.75-μm-wide slab-coupled rib guides separated by 4.25μm have been fabricated in GaAs. The performance of these couplers at 1.28 μm is in close agreement with that predicted using a modified effective-index method to obtain an approximate analytical solution for this type of coupler. The coupling length needed to symmetrically transfer power from the center guide to the two outside guides was 3.2 mm. At this length, less than 1 percent of the power remained in the center guide. The length needed to transfer power from one outside guide to the other outside guide was ≈ 6.4 mm, which isapprox sqrt{2}- times that of a similar two-guide coupler and twice that required to couple power from the center guide to the two outside guides. The power transfer efficiency in this case is not as good as when power was inputted into the center guide. Three-guide couplers of this type should prove useful as power dividers and combiners, especially in cases where waveguide bend losses preclude the use of"Y"- junctions. They may also prove useful as replacements for two-guide couplers where either sharper transfer characteristics are desired or where losses due to waveguide bends are again unacceptable.  相似文献   

19.
Wavelength-flattened fused couplers   总被引:3,自引:0,他引:3  
Mortimore  D.B. 《Electronics letters》1985,21(17):742-743
A technique is reported for the fabrication of fused couplers, which yields devices having splitting ratios substantially independent of wavelength. A low-loss, stable, single-mode 2×2 port coupler has been fabricated using this technique. The coupler has 50/50% coupling at both 1.3 and 1.52 ?m and 50% ± 9% coupling over the wavelength range 1.23 to 1.57 ?m.  相似文献   

20.
The criteria for adiabatic power flow along tapered mismatched directional couplers are discussed. The authors present the coupled local normal mode equations for tapered mismatched directional couplers. From these, the authors derive an optimally short profile for obtaining quasi-adiabatic power propagation. Apart from the trivial case where the mismatch is a constant, this is the only known mismatch profile for which analytical solutions of the coupled local normal mode equations exist. Conditions for which an adiabatic coupler can be used to obtain approximately 100% power transfer from one core to the other are also given  相似文献   

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