Steering a laser beam is a well-studied method for attaining welds with better quality in reducing pores, spatters, and other defects. However, the steering frequency, the possible shapes, and the total power are limited. Mechanical scanners have speed and power restrictions; diffractive optical elements (DOE) and multi-core lasers have limited shape flexibility. Civan’s Dynamic Beam laser provides a High Power (up to 100 kW), Single Mode, Continuous Wave output with the ability to create arbitrary beam shapes and do beam steering at a speed of 10s of MHz. The Dynamic Beam is derived from using the Coherent Beam Combining (CBC) technology and the Optical Phased Array (OPA) technology. This combination allows to dynamically tailor beam parameters to the required application. The benefits of the Dynamic Beam are significant in many applications such as welding, cutting, drilling, and additive manufacturing. This is due to its ability to have better control of the melt pool and the keyhole, which both affect the quality of products. In cases where the melt pool is not stable, spatter and pores occur and damage the pieces.
The principles of coherent beam combining for multiple fiber laser amplifiers is presented and discussed, with a focus on the optical phased array (OPA) beam combining technique. Several unique properties of OPA beam combining such as real time control over beam scanning, beam shape, focal plane position and intensity modulation with a MHz bandwidth open up several important new degrees of freedom for materials processing applications, enabling higher throughput, more efficient operation and advanced processing techniques. A 16kW dynamic laser beam at 1064nm based on coherent combination of 32 parallel ytterbium doped fiber amplifiers is presented, together with some example beam profiles.
We demonstrate intra-fiber couplers performance that is close to complete brightness preservation up to 3kW. Furthermore, when mutually coherent sources were used, the same couplers were able to achieve brightness enhancement with almost no beam quality (BQ) deterioration. The couplers are based on an adiabatic, all-fiber, mode coupling device preserving the lowest spatial mode orders. Brightness levels that approach the theoretical limits were achieved by compressing the participating modes into a tight cross section. Incoherent combination is shown for 2×1, 3×1 and 7×1 combined elements. Additionally, we present a solution for preserving the beam propagation factor of the coupler by using a specialty engineered core delivery fiber. The fabricated components are fully fiber- integrated, hence, without free-space limitations. An overall transmission of <90% was obtained, while the coupler-delivery connection is responsible for less than 0.5% loss. Consequently, relatively low temperatures were observed in the combiner package. Alternatively, utilizing two mutually coherent sources, a quadratic brightness factor improvement was demonstrated. The scheme does not require polarization preserving fibers, and achieved rugged 'in-phase' mode-locking. This allows for a significantly simplified scheme, compared to common coherent combining methods. Prospect on future trends relating to nonlinearities and thermal load management are discussed.
Eyal Shekel, Shlomo Ruschin, Daniel Majer, Jeff Levy, Guy Matmon, Lisa Koenigsberg, Jacob Vecht, Amir Geron, Rotem Harlavan, Harel Shfaram, Arnon Arbel, Tom McDermott, Tony Brewer
We report here a scalable, multichassis, 6.3 terabit core router, which utilizes our proprietary optical switch. The router is commercially available and deployed in several customer sites. Our solution combines optical switching with electronic routing. An internal optical packet switching network interconnects the router’s electronic line cards, where routing and buffering functions take place electronically. The system architecture and performance will be described.
The optical switch is based on Optical Phased Array (OPA) technology. It is a 64 x 64, fully non-blocking, optical crossbar switch, capable of switching in a fraction of a nanosecond. The basic principles of operation will be explained. Loss and crosstalk results will be presented, as well as the results of BER measurements of a 160 Gbps transmission through one channel.
Basic principles of operation and measured results will be presented for the burst-mode-receivers, arbitration algorithm and synchronization.
Finally, we will present some of our current research work on a next-generation optical switch.
The technological issues we have solved in our internal optical packet network can have broad applicability to any global optical packet network.
Information theory is used to predict an optimal spatial distribution of a given number of photodetectors. We compare our results with the known distribution in the human eye. The optimization takes into account eye movement which leads to different optimal arrays depending on the time scales of the visual information. When the visual data contains mixed time scales, maximum information flow is achieved by an array distribution consisting of both a large uniform low resolution region, and a smaller high resolution region, as in the human retina. Optimal ratios of areas and densities of these two regions are calculated as a function of the number of eye movements. The results lend support to the hypothesis that the retina is an information theoretically optimal processor.
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