DE19821245C1 - Optical multiplexer and optical demultiplexer - Google Patents

Abstract

Optical multiplexer (MUX) and optical demultiplexer (DMUX) with a cascade-like structure based on the principle of the binary tree. In the demultiplexer, a transmission band (lambda¶1-8¶) is divided into a lower subband (lambda¶1-4¶) and an upper subband (lambda¶5-8¶) in a first optical filter FD1. The subbands are divided into further subbands (lambda¶1, ¶ ¶2¶, ... lambda¶7, ¶ ¶8¶) or into transmission channels (lambda¶1¶-lambda¶8¶). DOLLAR A In the multiplexer, individual transmission channels are combined in a corresponding manner. The low insertion loss and the gradual expandability are advantageous.

Description

Optical transmission systems are increasingly using the wavelength gene multiplexing method, in which several channels with under different wavelengths over the same transmission path be transmitted. At the beginning of the route, the individual Channels are merged into a transmission band that again divided into individual channels at the end of the route becomes.

In previously used wavelength division multiplex transmission systems, the channels are for example using a non-wavelength selective power splitter fiber coupler (Power Combiner) merged or by appropriate Splinters separated. These components can be used without a need fit for a variety of wavelength combinations turn, their main disadvantage is the high insertion cushioning.

Demultiplexer, implemented with 1: N couplers and filters also have high damping. Such a Multiplexer / demultiplexer for three wavelengths is from the Publication DE 43 02 133 A1 known by Kaska dation of two multiples designed as fusion couplers xern / Demultiplexern by utilizing the optical transmission supply properties of monomode fibers is formed.

Another arrangement is known from the patent specification DE 40 41 047 C2 known for demultiplexing. A light signal with under different wavelengths initially becomes a parallel beam bundled and at an acute angle guided light-wave-selective element, where appropriate after multiple reflections signals with different Wavelengths can be selected.

The object of the invention is optical multiplexers and demul Specify tiplexer with low damping.

This task is solved by the independent claims.

The advantage of this solution is not only the small one Insertion loss, the multiplexer or demultiplexer can also gradually expanded according to the requirements become.

Advantageous developments of the invention are in the Un claims specified.

Exemplary embodiments of the invention are described below explained in more detail by figures.

Show it:

Fig. 1 is an optical demultiplexer according to the invention and

Fig. 2 shows an optical multiplexer according to the invention.

The demultiplexer DMUX shown in FIG. 1 is designed as a filter cascade which has the structure of a binary tree. Each filter has an input and two outputs, each of which is connected to inputs of filters of the next filter stage. Accordingly, the number of filters doubles in each subsequent stage.

An input DE of the optical demultiplexer DMUX or the first filter F1 is supplied with a transmission band λ _1-8 and divided into a lower subband λ _1-4 and an upper subband λ _5-8 . In the next filter stage, a second filter FD2 divides the lower sub-band into two further sub-bands λ _1,2 and λ _3,4 which are adjacent in terms of wavelength; Accordingly, the upper subband is divided in a third filter FD3 into likewise adjacent further adjacent subbands λ _5.6 and λ _7.8 . The lower and upper sub-band are thus in each case again lower in another and another obe res subband split Each of these other sub-bands in a third and final here filter stage by filters FD4 to FD7 in two wavelength moderately adjacent transmission channels λ _1, λ ₂ to λ ₇ , λ ₈ divided, which are output at the outputs DA1 to DA8.

Wavelength filters can be used as filters the combination of a high pass and a low pass speak. Of course, all or part of it Bandpass filters are used to prevent interference suppress outside the wavelength ranges used.  

In Fig. 2, an optical multiplexer MUX is shown, which is also realized as a filter cascade with the same tree structure. The filters each have two inputs ME1, ME2; ... and an output MA on. The first filter stage FM4 to FM7 is used to combine two adjacent transmission channels λ ₁ , λ ₂ ; λ ₃ , λ ₄ , ... to λ ₇ , λ ₈ .

The respective wide sub-bands λ ₁ , λ ₂ to λ ₇ , λ ₈ output at the output of one of these filters are combined into a lower sub-band λ _1-4 and an upper sub-band λ _5-8 in the filters FM2 and FM3 and in one combined first filter FM1 to the transmission band λ _1-8 , which is delivered at the output MA of the multiple xer.

The number of transmission channels usually corresponds to one Po tenz von 2. The optical multiplexer or demultiplexer can of course also realized for any number of channels become.

The filters used are known components that are used in for example from the company E-TEK Dynamics, ENC., 1855 Lundy Avenue, San Jose, CA 95131 USA.

Demultiplexers and multiplexers can be built modularly and expanded according to the number of transmission channels required. In the simplest case, only two channels, for example λ ₁ and λ ₅ , can be transmitted, for which purpose only the filters FM1 and FD1 are required. In a first stage He can use the filters FM2 and FM5 and FD2 and FD5 four channels, z. B. λ ₁ , λ ₃ , λ ₅ , and λ ₇ , are transmitted, etc.

Claims (6)

1. Optical wavelength demultiplexer (DMUX) for dividing a transmission band (λ _1-8 ) into transmission channels (λ ₁ -λ ₈ ), characterized in that
that it is formed as a filter cascade with optical filters (FD1-FD7), each of which has one input and two outputs,
that a first filter (FD1) is provided, through which a transmission band (λ _1-8 ) is divided into a lower sub-band (λ _1-4 ) and an upper sub-band (λ _5-8 ), and
that further filters (FD2, FD3; FD4-FD7) are provided, through which the subbands (λ _1,2 , λ _5-8 ) into further upper and lower neighboring subbands (λ _1,2 , λ _3,4 ; λ _5.6 , λ _7.8 ) or in a single transmission channels (λ ₁ , λ ₂ , λ ₃ , ... λ ₈ ) who the. 2. Optical wavelength demultiplexer according to claim 1, characterized in that 2 ^N (N = 2, 3, 4, ...) outputs are provided. 3. Optical wavelength demultiplexer according to claim 1 or Claim 2, characterized, that it has a modular structure and at least one filter stage fe (FD4-FD8) is expandable. 4. Optical multiplexer (MUX) for combining several transmission channels (λ ₁ -λ ₈ ), characterized in that
that it is designed as a filter cascade with optical filters (FM1-FM7), each having two inputs (ME1, ME2; ...) and one output,
that adjacent transmission channels (λ ₁ , λ ₂ ; λ ₃ , λ ₄ ; ...) are present at the inputs of the input filters (FM4-FM7), which initially lead to other adjacent subbands (λ _1,2 ; λ _3,4 ; ...) are summarized,
that further filters (FM2, FM3; FM1) are provided, through which the further adjacent subbands (λ _1,2 ; λ _3,4 ; ...) to more comprehensive subbands (λ _1-4 ; λ _5-8 ) or to a transmission band (λ _1-8 ) can be summarized. 5. Optical wavelength multiplexer according to claim 4, characterized in that 2 ^N (N = 2, 3, 4 ...) inputs are provided. 6. Optical wavelength multiplexer according to claim 4 or Claim 5 characterized, that it is modular and by at least one more Filter stage (FM4-FM7) is expandable.