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Optical time multiplexing device Disclosure Number: IPCOM000015641D
Original Publication Date: 2002-Jan-13
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 63K

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*Main Idea

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Optical time multiplexing device

*Main Idea

In optical telecommunications, pulsed signals on which data can be modulated are used. Increasing bandwidth demand leads to higher and higher modulation frequencies (bit rates). It hence is desirable to generate a pulse train with higher frequency by multiplying the frequency of a pulse train with lower frequency. This document describes an optical waveguide device that increases the bit rate of an incoming pulse train by a factor of 2, 4, 8, 16, etc. Furthermore, the document describes a device layout including a modulator that enables a signal power recovery up to 3 dB (a factor of two) as compared to a system in which the device alone is applied.

The device is built in optical waveguide technology and consists of a series of couplers and delay lines as shown in figure 1. The gray lines are the optical waveguides, the section where they come close together are the couplers and the delay lines are indicated by DL.

Fig. 1: Pulse multiplexer design

In order to achieve a pulse multiplication of 2^N, with N=1,2,3,... , the device consists of N+1 couplers and N delay lines. The picture presented in figure 1, shows the situation for N=2. The arm length differences of the delay lines are changed by factors of 2. The way the bit rate multiplication is achieved, is clarified by the red, green, yellow and black line. The first coupler splits an incoming pulse, and the delay line introduces a time delay of half the pulse period b...