The 300-pin Multi Source Agreement (MSA) and other MSAs provide basic requirements from a transponder or transceiver used in 10Gb/s optical networks. These MSAs typically address a wide range of applications, including: SONET/SDH, 10GbE and 10GFC for Metro, long-haul (LH) and ultra-long-haul (ULH) networks. Nonetheless, being a basic standard, the 300-pin MSA addresses the minimal required specifications set and does not cover the whole set of requirements and applications that system vendors are interested in. For example, widely tunable and extended reach transponders are not included in the 300-pin MSA.
Chromatic dispersion is one of the major reach limiting factors in optical networks. In reconfigurable optical networks, chunks of DWDM channels may travel through different routes and therefore require tunable dispersion compensation. In static ULH optical networks, the number of dispersion compensation fibers (DCFs) dictates the amount of residual chromatic dispersion. This residual chromatic dispersion differs from one DWDM channel to the other. Unless it is compensated at the receiver, it further restricts the link length and reduces the distance between one regenerator to the other. This results in shorter links and more O-E-O blocks, which dramatically increases the cost of the network. This paper discusses a specially designed optical dispersion compensation (ODC) device that is packaged in a standard butterfly package and can fit into a 300-pin MSA transponder. A transponder with the proposed ODC can still satisfy all the basic requirements that are described in the 300-pin MSA while providing improved chromatic dispersion tolerance.
In this paper we present ultra fast variable optical attenuator to be used for improved performance laser welding systems and for increasing the measurement performance in laser range finders and LIDARs. The improvement in laser range and LIDAR systems is caused due to preventing the reflection of light from the optics of the transmitter that saturates the receiver and thus limits the minimal detection range.
This paper presents innovative concepts related to the realization of ultra-fast optical switches, which are to be used in next-generation optical networks. Experimental measurements, which characterize the performance and reliability of such switches, are presented.
The paper presents several tunable devices used for optical spectral performance monitoring. The first type of devices is constructed out of a Fabry-Perot resonator filled with liquid crystal that is to be used for performing the spectral scanning. Another type of filters is based on birefringent filters to be applied for spatial imaging systems. The paper presents the design of the devices as well as its anticipated performances.
Optical signal processing has its roots in the experiments of Lord Rayleigh, Abbe and Porter that were the first that dealt with the spectrum of an image. This historical path of revolution has been followed years later by the extraordinary work of A. W. Lohmann in the optical data processing during the last 40 years. The new innovations and the future possibilities that are to be opened up in the new millennium show his dominant signature. Some recent projects that enlighten the future ofthe optical signal processing field are described in this presentation. The invention of the computer generated holograms (CGH) was a giant leap for the optical signal processing field. Filters and holograms that previously were generated by direct holographic recording means, have been all of a sudden replaced by synthetic functions designed and realized by digital computers. It was the first interface between digital computers and optical systems. Such an approach led to the design of opto-electronic systems that operate in perfect synergy where each element is utilized for what it does best. Along the years, the field of computer-generated holography has been expanded to what is known as: diffractive optical elements. Techniques like kinoforms, binary optics, on-axis CGH, etc. have been developed for addressing the growing application list ofsuch elements. CGHs highly affected the optical signal-processing field. For example, various new processing techniques were created and applied for invariant pattern recognition (Circular Harmonics (CH), Synthetic Discriminate Filters (SDF) etc). The next innovation wave reached the shores of the optical data processing community in the 80s when A. W. Lohmann presented the optical interconnections as the next challenge of optical data processing. Many configurations were discussed, investigated and applied for optical processing (perfect shuffle, omega net, cross over etc.). In the 90s A. W. Lohmann was a key player in a new revolution in optical processing where optics was used as a transformation tool. New transformations were invented and realized by optical means as for instance Fractional Fourier Transform, Wigner distribution, Fractional Hubert and Hartley Transforms etc. Those were applied for various signal-processing applications and used also in digital processing. In the new millenium optics adapts itself to the binary mode of operation that is common in computer systems. This trend becomes feasible also due to the impressive progress in the opto-electrical interface devices such as the spatial light modulators, light sources such as VCSELs and detectors such as photo-diodes. These new achievements permit also the operation of opto-electronic systems at extremely high rates. It is evident that in the next years of the millenium optical data processing field will continue to grow, develop and replace additional processing modules in the digital computation world. Without much doubt those will be accompanied and innovated by the scientific assistance foundation and guidance of A. W. Lohmann. In this paper we will focus on optical processing of partially coherent light. This field is mostly interesting and relevant since it includes both the aspects of data processing and the optical design skills that insure its promising industrial future.
Coherent light is the most popular carrier of a signal in an optical information processing system. The matched filtering system (Van Der Lugt 1965) is a prominent example. However, coherent optics is experimentally delicate, not well suited for unfriendly environments. As a reaction to this dilemma some new systems, that use totally incoherent light, have been presented recently. Those systems work reasonably well. But they can handle only real-valued non-negative signals, directly. An alternative approach is to use partially- coherent light. Now the optical system is not anymore as fragile as a coherent system. And the signals, which are now implemented as coherence functions, can be complex, in contrast to incoherent optics. However, the hardware of partially coherent systems is more elaborate.
A beam propagating in free space is exposed to the laws of diffraction, which tend to deform the wave front. Hence, 3D beam forming is a very applicable task. For instance it may be useful in designing a special beam to be used for scanning purposes, beam forming for optical communication modules and 3D beam forming as a tool to exceed system's resolving power. There are several techniques, which allow obtaining a reduced sensitivity to diffraction in a pre- determined region of propagation. In this paper a novel optimal technique is suggested. Using the calculus of variation method we derive an analytic expression for an optimal filter in the mean square error sense, to obtain a 3D beam forming, which is as close as possible to the desired 3D distribution. We applied the proposed method for obtaining a scanning beam with improved performances. The suggested approach was tested in computer simulations as well as in optical experiments and was proven to deliver improved performance. Thus one can obtain an extended working region using the resulting beam with confined lateral spread.
This project deals with a novel approach for exceeding the resolving power of optical systems. The concept is based on a moving pre-designed, pseudo random, quasi-periodic grating that is located close to the object. The scanning property of the observing CCD camera is used for performing the final high-resolution restoration of the object.
This paper introduces a system that provides estimations for the 2-D or 3-D position of a point target, with high spatial resolution. The system contains a conventional imaging lens being attached to a special diffractive optical element. The super resolved position estimation to be utilized with pixelated detector arrays is obtained due to the use of this optical element, which replicates the imaged point source on the detector array plane. A relatively simplified computation algorithm applied on the composite image yields the desired position estimation.
The morphological correlation is the optimal method for searching a reference object in an input scene when the figure of merit is based on the mean absolute error (MAE). In practice, it was found that the morphological correlation exhibits high discrimination ability between similar patterns in recognition systems. It is based on threshold slicing the input image as well as the reference filter into many binary slices, as many as the dynamic range of the input permits. The threshold slices of the input and the reference are then correlated and summed up to obtain the morphological correlation. This operation is characterized by a sharp correlation peak but requires many correlation operations. In this work we propose a novel correlation operation that is characterized by even higher discrimination capabilities than exhibited by the conventional morphological correlation and requires less computational effort. The method is based upon the binary representation of the gray level of each pixel in the image. For example: if the dynamic range allows the definition of 256 levels, i.e., 8 binary bits, then a level of 10 will be represented as 00001010. Unlike the morphological correlation, the proposed modification is based on correlating binary slices that are the bitmap representations. Thus, only 8 slices of the input and the reference are required and only 8 correlations rather than 256 performed. The optical implementation of the new approach is fairly simple and can be utilized via the well-known joint transform correlator architecture. Experimental results demonstrate the advantages of the suggested method.
Morphological correlation is a novel method for obtaining high discrimination ability in pattern recognition applications. It provides also important abilities for image compression and image analysis. The concept is based on slicing the input image and the reference filter into many binary slices, e.g. 255, and correlating them. The morphological correlation is defined as the summation of these correlations. The morphological correlation is characterized by a sharp correlation peak narrower than that exhibited by matched filter. The disadvantages are the requirements of performing many correlations and its very high sensitivity to noise added to the reference image. In this presentation we suggest two methods to solve both drawbacks. First, instead of 255 correlations we suggest to utilize only 8, by representing the grey level of each pixel by its 8 bit binary representation. Then, 8 binary masks are constructed according to the binary representation. In order to address the problem of severe sensitivity to noise, we suggest to sum the 255 correlations of the morphology slices while each slice is multiplied by a weighting factor which equals the correlation peak of that specific slice with noise divided by its correlation peak value when no noise is added. The solutions suggested here were examined by computer simulations demonstrating considerable improvements in the performance of the morphological correlator.