Silicon slow-light-based photonic mixer for microwave-frequencyconversion applications

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.001721. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] We describe and demonstrate experimentally a method for photonic mixing of microwave signals by using a silicon electro-optical Mach¿Zehnder modulator enhanced via slow-light propagation. Slow light with a group index of ~11, achieved in a one-dimensional periodic structure, is exploited to improve the upconversion performance of an input frequency signal from 1 to 10.25 GHz. A minimum transmission point is used to successfully demonstrate the upconversion with very low conversion losses of ~7¿¿dB and excellent quality of the received I/Q modulated QPSK signal with an optimum EVM of ~8%.Financial support from FP7-224312 HELIOS project and Generalitat Valenciana under PROMETEO-2010-087 R&D Excellency Program (NANOMET) are acknowledged. F. Y.Gardes, D. J. Thomson, and G. T. Reed are supported by funding received from the UK EPSRC funding body under the grant “UK Silicon Photonics.” The author A. M. Gutiérrez thanks D. Marpaung for his useful help.Gutiérrez Campo, AM.; Brimont, ACJ.; Herrera Llorente, J.; Aamer, M.; Martí Sendra, J.; Thomson, DJ.; Gardes, FY.... (2012). Silicon slow-light-based photonic mixer for microwave-frequencyconversion applications. Optics Letters. 37(10):1721-1723. https://doi.org/10.1364/OL.37.001721S17211723371

Coherent states for continuous spectrum operators with non-normalizable fiducial states

The problem of building coherent states from non-normalizable fiducial states is considered. We propose a way of constructing such coherent states by regularizing the divergence of the fiducial state norm. Then, we successfully apply the formalism to particular cases involving systems with a continuous spectrum: coherent states for the free particle and for the inverted oscillator $(p^2 - x^2)$ are explicitly provided. Similar ideas can be used for other systems having non-normalizable fiducial states.Comment: 17 pages, typos corrected, references adde

Generation of Ultrastable Microwaves via Optical Frequency Division

There has been increased interest in the use and manipulation of optical fields to address challenging problems that have traditionally been approached with microwave electronics. Some examples that benefit from the low transmission loss, agile modulation and large bandwidths accessible with coherent optical systems include signal distribution, arbitrary waveform generation, and novel imaging. We extend these advantages to demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. This provides a 10 GHz electrical signal with fractional frequency instability <8e-16 at 1 s, a value comparable to that produced by the best microwave oscillators, but without the need for cryogenic temperatures. Such a low-noise source can benefit radar systems, improve the bandwidth and resolution of communications and digital sampling systems, and be valuable for large baseline interferometry, precision spectroscopy and the realization of atomic time

Observation of phase noise reduction in photonically synthesized sub-THz signals using a passively mode-locked laser diode and highly selective optical filtering

A Continuous Wave (CW) sub-THz photonic synthesis setup based on a single Passively Mode-Locked Laser Diode (PMLLD) acting as a monolithic Optical Frequency Comb Generator (OFCG) and highly selective optical filtering has been implemented to evaluate the phase noise performance of the generated sub-THz signals. The analysis of the synthesized sub-THz signals up to 120 GHz gives as a result an effective reduction of the electrical linewidth when compared to direct harmonic generation that begins at 50 GHz and becomes greater as the frequency increases. The phase noise reduction offered by the setup, along with its integration potential, cost and bandwidth, make it a promising candidate to the development of an integrated and high performance low phase noise local oscillator in the sub-THz range.Work supported by the Spanish Ministry of Science and Technology through the project TEC2009-14525-C02-02 and by the European Commission FP7 iPHOS Project. The work by A.R. Criado has been supported by the Spanish Ministry of Science and Technology under the FPI Program, Grant# BES2010-030290.Publicad

Proposed flat-topped pulses bursts generation using all-pass multi-cavity structures

We propose a simple lossless method for the generation of flat-topped intensity pulses bursts from a single utrashort pulse. We have found optimum solutions corresponding to different numbers of cavities and burst pulses, showing that the proposed all-pass structures of optical cavities, properly designed, can generate close to flat-topped pulse busts

All-pass optical structures for repetition rate multiplication

We propose and analyze several simple all-pass spectrally-periodic optical structures, in terms of accuracy and robustness, for the implementation of repetition rate multipliers of periodic pulse train with uniform output train envelope, finding optimum solutions for multiplication factors of 3, 4, 6, and 12

Reconfigurable lattice mesh designs for programmable photonic processors

© 2016 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited[EN] We propose and analyse two novel mesh design geometries for the implementation of tunable optical cores in programmable photonic processors. These geometries are the hexagonal and the triangular lattice. They are compared here to a previously proposed square mesh topology in terms of a series of figures of merit that account for metrics that are relevant to on-chip integration of the mesh. We find that that the hexagonal mesh is the most suitable option of the three considered for the implementation of the reconfigurable optical core in the programmable processor.The authors wish to acknowledge the financial support given by the Research Excellency Award Program GVA PROMETEO II/2013/012, Spanish MINECO projects TEC2013-42332-P PIF4ESP, TEC2015-69787-REDT PIC4TB and TEC2014-60378-C2-1-R MEMES, as well as the projects FEDER UPVOV 10-3E-492 and FEDER UPVOV 08-3E-008. The work of D. Perez was supported by the FPI-UPV Grant Program from the Universitat Politecnica de Valencia and the work of I. Gasulla was supported by the Spanish MINECO through the Ramon y Cajal Program. R. Soref is supported by the Air Force Office of Scientific Research.Pérez-López, D.; Gasulla Mestre, I.; Capmany Francoy, J.; Soref, RA. (2016). Reconfigurable lattice mesh designs for programmable photonic processors. Optics Express. 24(11):12093-12106. https://doi.org/10.1364/OE.24.012093S12093121062411Birth of the programmable optical chip. (2015). Nature Photonics, 10(1), 1-1. doi:10.1038/nphoton.2015.265Capmany, J., & Novak, D. (2007). Microwave photonics combines two worlds. Nature Photonics, 1(6), 319-330. doi:10.1038/nphoton.2007.89Yao, J. (2009). Microwave Photonics. Journal of Lightwave Technology, 27(3), 314-335. doi:10.1109/jlt.2008.2009551Mitchell, J. E. (2014). Integrated Wireless Backhaul Over Optical Access Networks. Journal of Lightwave Technology, 32(20), 3373-3382. doi:10.1109/jlt.2014.2321774Smit, M., Leijtens, X., Ambrosius, H., Bente, E., van der Tol, J., Smalbrugge, B., … van Veldhoven, R. (2014). An introduction to InP-based generic integration technology. Semiconductor Science and Technology, 29(8), 083001. doi:10.1088/0268-1242/29/8/083001Pérez, D., Gasulla, I., & Capmany, J. (2015). Software-defined reconfigurable microwave photonics processor. Optics Express, 23(11), 14640. doi:10.1364/oe.23.014640Capmany, J., Gasulla, I., & Pérez, D. (2015). The programmable processor. Nature Photonics, 10(1), 6-8. doi:10.1038/nphoton.2015.254Zhuang, L., Roeloffzen, C. G. H., Hoekman, M., Boller, K.-J., & Lowery, A. J. (2015). Programmable photonic signal processor chip for radiofrequency applications. Optica, 2(10), 854. doi:10.1364/optica.2.000854Liu, W., Li, M., Guzzon, R. S., Norberg, E. J., Parker, J. S., Lu, M., … Yao, J. (2016). A fully reconfigurable photonic integrated signal processor. Nature Photonics, 10(3), 190-195. doi:10.1038/nphoton.2015.281Soref, R. (2014). Mid-infrared 2 × 2 electro-optical switching by silicon and germanium three-waveguide and four-waveguide directional couplers using free-carrier injection. Photonics Research, 2(5), 102. doi:10.1364/prj.2.000102Roeloffzen, C. G. H., Zhuang, L., Taddei, C., Leinse, A., Heideman, R. G., van Dijk, P. W. L., … Boller, K.-J. (2013). Silicon nitride microwave photonic circuits. Optics Express, 21(19), 22937. doi:10.1364/oe.21.02293