The encryption method uses a spatial light modulator which converts light pulses representing original data into pseudo. Figure 1 shows the construction of such a compressor. Wai3 1photonics division, department of physics, school of advanced sciences, vit university, vellore 632 014, tamil nadu, india 2school of engineering, fraser noble building, kings college. Ultrashort pulse compression using photonic crystal fibre. An optical image encryption technique based on compressive sensing using fully optical means has been proposed.
Optical pulse compression and its effects using fiber. At present, the compression method that is achieving parabolic pulse with linear chirp and compensating the linear chirp is paid more attention. It is shown that the function measured with this device is an. Definition of terms part 772page 6 export administration regulations bureau of industry and security march 9, 2020 technical note at the end of category 4 of the. Highpower femtosecond optical pulse compression by using spatial solitons d.
Optical image compression and encryption methods a. A modification to this is the softknee compressor where the ratio increases progressively as the signal approaches the threshold, the end result being a less assertive, less obtrusive form of compression. This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse. Rp photonics encyclopedia pulse compression, shortening. Over the years extensive studies have been carried out to apply coherent optics methods in realtime communications and image transmission. Antijamming design and analysis of a novel pulse compression radar signal based on radar identity and chaotic encryption. Especially to compress a pulse to near the transform limit one should not. Optical pulse compression in fiber bragg gratings eprints soton. In a first step, the optical bandwidth is increased, typically with a nonlinear interaction such as selfphase modulation. In these techniques a long duration pulse is used which is either phase or frequency modulated before transmission and the received signal is passed through a. The real magic in an optical compressor as an audio device lies in the photocell, however. Opticalpulse compression article about opticalpulse. An optical image compression and encryption scheme based.
May 20, 2015 an optical image encryption technique based on compressive sensing using fully optical means has been proposed. Optical pulse compression using highorder dispersion compensation is proposed and theoretically analyzed. This is especially true when a large amount of information needs to be processed, e. Introduction over the years intensive research has been directed toward coherent optics, especially the issues of compression and encoding, because of the potential for new technological applications in telecommunications. Pdf antijamming design and analysis of a novel pulse. The rp photonics buyers guide contains 19 suppliers for pulse compressors. Pulse compression method for radar signal processing. Numerical results are presented for the achievable compression and compressed. We report the first experimental demonstration of the optical pushbroom a novel type of alloptical pulse compression. Volume 56, number 3 optics communications 1 december 1985 compression of amplified chirped optical pulses donna strickland and gerard mourou l. Pedestal free pulse compression of chirped optical solitons. Hydrated electron dynamics explored with 5fs optical pulses rug. High speed all optical switching and encryption using ultrafast devices.
A prism compressor is an optical device used to shorten the duration of a positively chirped ultrashort laser pulse by giving different wavelength components a different time delay. The first 50% of its release occurs very rapidly generally measured in tens of milliseconds, and a complete release that can take several seconds. Leaird bellcore, 331 newman springs road, red bank, new jersey 07701 received may 1, 1991 we demonstrate a novel pulse compression technique that uses the selfconfinement of twodimensional spatial. Development of radar pulse compression techniques using. Osa compression of optical pulses chirped by selfphase. The object beam first illuminates an object image that is used for encryption and subsequently passes through two random phase masks and to perform the encryption using the drpe method. The photocell has a gradual and predictable release curve, which is very gentle and musical. The pulse is characterized by its pulse width, which in the case of a pulse compression radar is called the uncompressed pulse width, t. Compression of optical pulses chirped by selfphase modulation in fibers. Mode locked pulse generation has been reported using both active and.
Pulse compression, fiber communications, and diffraction. Lebedev institute of solid state physics, ras, 142432, chernogolovka, moscow distr. Singlediffractiongrating and grism pulse compressors. Several researchers have carried out experiments to either compress the optical temporal width or. Pulse compression, the compromise transmit a long pulse that has a bandwidth corresponding to a short pulse must modulate or code the transmitted pulse to have sufficient bandwidth, b can be processed to provide the desired range resolution.
We report the results of a theoretical analysis of this process. Firstly, the required dispersion profile for the highorder dispersion compensation is derived, according to the linear chirp and the nonlinear chirp of a phasemodulated continuouswave cw laser source. Compression of positively chirped pulses also happens in negative dispersion anomalous regime 5. The shortening of the duration of an optical pulse by techniques similar to those used in chirp radar, in which a frequency sweep is imposed on the pulse. The ideal device for carrying out this program has not been developed. Picosecond and femtosecond fourier pulse shape synthesis.
Optical pulse compression with diffraction gratings pdf. Pulse compression allows one to generate pulses of long duration minimizing damage problems and subsequently compress optical. Data encryption of optical fibre communication using. High speed all optical switching and encryption using ultrafast. Optical encryption is a means of securing inflight data in the transport layer of the network as it is carried over optical waves across fiberoptic cables. Definition of terms part 772page 6 export administration regulations bureau of industry and security august3, 2018 772. With the use of the highorder dispersion compensation, such as the combination. Pulse compression allows one to generate pulses of long duration minimizing damage problems and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. Wai c a photonics division, department of physics, school of advanced sciences, vit university, vellore 632 014, tamil nadu, india. In this case, one usually desires strongly positively chirped pulses at the input. Pulse stretching and compressing using grating pairs. Pedestal free pulse compression of chirped optical solitons k. Optical pulse your brampton optometrists and optical store.
Taraprasad chattopadhyay department of physics visvabharati university santiniketan, west bengal, india. Lasers and related devices have been found to have an amazing potential for generating light pulses with very special properties there is a wide range of techniques for generating pulses with durations of nanoseconds, picoseconds, or even femtoseconds with lasers. Highpower femtosecond optical pulse compression by using. An efficient time lens for optical pulse compression. This pulse width is one of the critical characteristics of the pulse compression radar. Pdf we study the shaping of picosecondduration optical pulses by the. Hence, the total key space of the proposed optical image compression and encryption scheme is greater than 8. Pulse shaping, compression, and pedestal suppression employing a. Swamp optics tutorial pulse compression recall that different colors propagate at different velocities so that, after passing through the material, different colors experience different delays, a ubiquitous effect called groupdelay dispersion gdd. Singledispersiveelement pulse compressors our singlediffractiongrating pulse compressor uses only three elements.
Figure 5 shows the optical fiber dispersions parameters. If you compress after encryption and the compression does any good i. The compressive optical image encryption system is shown in fig. Network services should be easy to deploy and scale for both the service provider and customer. Compressive optical image encryption scientific reports. Limits of fibergrating optical pulse compression osa. So replacement of bulk diffraction grating in compressor part can be possible if the desired compression of pulse obtained by controlling the pulse as well as the optical fiber parameters. For wavelengths less than those used in telecommunications about 1. Encrypted text ought to be indistinguishable from randomness. The unique optical properties of this novel medium in terms of high non linearity and relatively small group velocity dispersion are shown to provide an ideal. Optical pulse article about optical pulse by the free. In most cases, this leads to chirped pulses, often with a duration which is even larger than the original pulse duration. The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy.
Weve equipped our office with stateoftheart technology and amenities. Optical pulse compression with diffraction gratings. Osa optical image compression and encryption methods. In summary, due to the key sensitivity and larger key space, the proposed optical image compression and encryption scheme can resist the bruteforce attack. The use of selfphase modulation in a singlemode fiber to chirp an optical pulse, which is then compressed with a gratingpair compressor, has been shown to be a practical technique for the production of optical pulses at least as short as 30 fsec. Optical pulse compression using the combination of phase. Chirped pulse amplification perhaps the most common use of grating stretchers and compressors is in chirped pulse amplification. Optics communications vol 307, pages 1110 15 october 20. It is shown that the fiber and gratingpair pulse compression technique is limited by higherorder terms in the response of the.
In the optical pushbroom high intensity pump pulses, tuned well away from the resonance of a bragg grating, modify the transmission of a weak probe tuned near to the gratings photonic bandgap. A short flash of light, used to isolate moments of time. A laser beam is split into an object beam and a reference beam. Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. Simulation of optical pulse compression using parabolic pulse.
However, in optical pulse compression, the pulse bandwidth will broaden significantly. Encryption and compression of data information security. Optical pulse compression and its effects using fiber bragg. The analogy between optical pulse compression and optical. The recent progress in dataprocessing networks and communication systems has considerably increased the capacity of information exchange. The analogy between optical pulse compression and optical coherence transformation m. Pdf pulse shaping, compression, and pedestal suppression. Abstract a new type of an optical interferometer is discussed the phase difference between the interfering beams in which is substantially wavelength dependent. Pulse shaping, compression, and pedestal suppression employing a nonlinear optical loop mirror article pdf available. Since the effect of pbg is not included in the nlse approximation, the optical pulse can continue to compress as long as the secondorder dispersion decreases exponentially. Find out information about optical pulse compression. Such pulses have a broadband optical spectrum, and can be created by modelocked oscillators.
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