Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1997-06-25
2001-03-06
Pascal, Leslie (Department: 2733)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200
Reexamination Certificate
active
06198557
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a telecommunication system having frequency-dividing optical components for parallel processing of optical pulses, and more particularly to the use of fiber gratings and photonic-crystals for the spatial distribution of the frequency-coded optical pulses.
RELATED TECHNOLOGY
Optical telecommunications nearly always take place through a sequence of individual, binary-coded light pulses. Since transmission frequencies are already advancing today into ranges which no longer permit electronic data processing, and especially not the complex encoding and decoding required of secret communications, there is a considerable need for optical elements which can read chronological bit sequences into a single- or multi-dimensional spatial areal, and then process them further in an optically parallel manner. An optical, parallel processor is capable of simultaneously transforming a large quantity of binary or analog signals, arranged as an image or a pattern and, thus, works considerably faster than an electronic computer. When working with areals (areas) of 1000×1000 optical points (pixels), a parallel processing of 10
6
signals can be readily achieved and serves as an exceptional time saver for certain numerical operations, such as a Fourier transformation. Since Fourier transformations comprise an essential component of machine pattern recognition, it is precisely the encoding and decoding of communications that could be realized easily and very quickly in terms of optics.
It is known that electro-optical components which read chronological pulse sequences into spatial areals have a Brownian tube type design. At the present time, as shown in German Patent No. 196 09 234.5 (H. Koops, filed March 1996), which is not necessarily prior art to the present invention, it is only in micro-tubes that electron beams are able to be deflected quickly enough to feed signals in the multi-gigahertz range.
Another method encodes the individual, optical pulses optionally with the aid of light polarization. The first, third, fifth, etc. of each odd-numbered pulse is polarized, for example, vertically, and all even-numbered pulses are polarized horizontally-linearly. The even and odd pulses are then able to be separated locally in each case with the aid of a polarizing beam splitter. Cascading renders possible a greater degree of separation. The advantage of this method is that the separating element- the beam splitter, is purely passive. After the pulses have been electro-optically polarization-encoded, for example, there is no longer a need for an active switching operation. Obviously, the drawback of the method is the small number of only two parallel channels per cascade stage.
SUMMARY OF THE INVENTION
The present invention is characterized by individual, successive optical pulses being frequency-encoded instead of polarization-encoded. Since the light frequency within an optical telecommunication window can be easily altered by 100 nm, and on the other hand, since semiconductor lasers are able to be detuned by several nanometers by varying the applied voltage, it is possible, in principle, for different frequencies to be assigned within a broad range to optical pulses. To this end, a plurality of semiconductor lasers having different center-of-mass frequencies should be electrically switchable with respect to their radiation frequencies. The resulting optical pulses having different frequencies are then binary-encoded for telecommunication purposes and are fed into the transmitting glass fiber. Thus, a sequence of pulses, the first having the frequency &ugr;
1
, is impressed upon the communication. Here, for example, it may be that &ugr;
1
<&ugr;
2
<&ugr;
3
< - - - <&ugr;
i
<&ugr;
i+1
< - - - <&ugr;
N
.
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Yu, F. et al., Photorefractive Fiber and Crystal Devices: Materials, Optical Properties, and Applications II, Proceedings, SPIE—The International Society for Optical Engineering, vol. 2849, pp. 248-256.
H. Koops, Photonic crystals built by three-dimensional aditive lithography enable integrated optic of high density, SPIE, vol. 2849/29 (Denver 1996).
Dultz Wolfgang
Frins Erna
Koops Hans
Meltz Gerald
Deutsche Telekom AG
Kenyon & Kenyon
Pascal Leslie
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