Design of array of diffractive optical elements with inter-element coherent fan-outs

Building on the optimal-rotation-angle method, an algorithm for the design of inter-element coherent arrays of diffractive optical elements (DOEs) was developed. The algorithm is intended for fan-out DOE arrays where the individual elements fan-out to a sub-set of points chosen from a common set of points. By iteratively optimizing the array of elements as a whole the proposed algorithm ensures that the light from neighbouring elements is in-phase in all fan-out points that are common to neighbouring DOEs. This is important in applications where a laser beam scans the DOE array and the fan-out intensities constitute a read-out of information since the in-phase condition ensures a smooth transition in the read-out as the beam moves from one DOE to the next. Simulations show that the inter-element in-phase condition can be imposed at virtually no expense in terms of optical performance, as compared to independently designed DOEs

Navigation in vehicle crash test using MEMS-based IMU

Results from our experiments on inertial navigation in crash testing of vehicles are presented. A custom designed inertial measurement unit (IMU) has been developed, and several tests in dummy calibration rigs including full-scale Euro NCAP collisions have been performed at our partners\u27 crash test laboratories. For reference, the IMU data is compared to camera data and traditional single-axis inertial sensors. \ua92010 IEEE

Terahertz Radiation Shaping Based on Third-Order Dispersion and Self-Phase Modulation in Standard Single-Mode Optical Fiber

Third-order dispersion and self-phase modulation in standard single-mode fibers are employed in a fiber-based THz time domain spectroscopy system for radiation shaping. Ultra-short optical pulses are converted into trains of pulses, thus shaping the THz radiation emitted by photoconductive antennas operating at telecom wavelengths. The proposed architecture allows narrowband and wideband THz emission as well as tunability of the central frequency. Since the shaping takes place in standard optical fiber the architecture could be potentially implemented without requiring any additional device. Experiments showing the principle of operation have been performed demonstrating tunability of the central frequency between 350 and 800 GHz and bandwidth from 150 GHz to the full bandwidth of the system.This work has been financially supported by the Spanish Ministerio de Ciencia e Innovacion TEC2009-08078. The work of J. Palaci was supported by the UPV-FPI program.Palací López, J.; Vidal Rodriguez, B. (2012). Terahertz Radiation Shaping Based on Third-Order Dispersion and Self-Phase Modulation in Standard Single-Mode Optical Fiber. Journal of Infrared, Millimeter and Terahertz Waves. 33(6):605-614. https://doi.org/10.1007/s10762-012-9896-8S605614336P.H. Siegel, IEEE Trans. Microwave Theory Tech. 50, 910 (2002).M. Tonouchi, Nature Photon. 1, 97 (2007).J. Faist, F. Capasso, D.-L. Sivco, C. Sirtori, A.-L. Hutchinson, A.-Y- Cho, Science 264, 5158 (1994).D. Saeedkia, S. Safavi-Naeini, J. Lightwave Technol. 26, 2409 (2008).B. Sartorius, H. Roehle, H. Künzel, J. Böttcher, M. Schlak, D. Stanze, H. Venghaus, M. Schell, Opt. Express 16, 9565 (2008).A.S. Weling, T.F. Heinz, J. Opt. Soc. Am. B 16, 1455 (1999).O. Levinson, M. Horowitz, J. Lightwave Technol. 21, 1179 (2003).J. Stigwall, A. Wiberg, IEEE Photon. Technol. Lett. 19, 931 (2007).S. Vidal, J. Degert, J. Oberlé, E. Freysz, J. Opt. Soc. B 27, 1044 (2010).G. P. Agrawal, Nonlinear fiber optics, 3rd edn. (Academic Press, 2001), p.1G. P. Agrawal, Nonlinear fiber optics, 3rd edn. (Academic Press, 2001), pp.49G. P. Agrawal, Nonlinear fiber optics, 3rd edn. (Academic Press, 2001), p.97G. P. Agrawal, Nonlinear fiber optics, 3rd edn. (Academic Press, 2001), pp.51-55J. Capmany, B. Ortega, D. Pastor, J. Lightwave Technol. 24, 201 (2006).E. Hellstrom, H. Sunnerud, M. Westlund, M. Karlsson, J. Lightwave Technol. 21, 1188 (2003)

Photonic ADC: overcoming the bottleneck of electronic jitter

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs - a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20-channel silicon filter bank has been demonstrated