Slow light bimodal interferometry in one-dimensional photonic crystal waveguides

[EN] Strongly influenced by the advances in the semiconductor industry, the miniaturization and integration of optical circuits into smaller devices has stimulated considerable research efforts in recent decades. Among other structures, integrated interferometers play a prominent role in the development of photonic devices for on-chip applications ranging from optical communication networks to point-of-care analysis instruments. However, it has been a long-standing challenge to design extremely short interferometer schemes, as long interaction lengths are typically required for a complete modulation transition. Several approaches, including novel materials or sophisticated configurations, have been proposed to overcome some of these size limitations but at the expense of increasing fabrication complexity and cost. Here, we demonstrate for the first time slow light bimodal interferometric behaviour in an integrated single-channel one-dimensional photonic crystal. The proposed structure supports two electromagnetic modes of the same polarization that exhibit a large group velocity difference. Specifically, an over 20-fold reduction in the higher-order-mode group velocity is experimentally shown on a straightforward all-dielectric bimodal structure, leading to a remarkable optical path reduction compared to other conventional interferometers. Moreover, we experimentally demonstrate the significant performance improvement provided by the proposed bimodal photonic crystal interferometer in the creation of an ultra-compact optical modulator and a highly sensitive photonic sensor.The authors acknowledge funding from the Generalitat Valenciana through the AVANTI/2019/123, ACIF/2019/009 and PPC/2020/037 grants and from the European Union through the operational program of the European Regional Development Fund (FEDER) of the Valencia Regional Government 2014-2020. We also thank Pablo Sanchis and Irene Olivares for their helpful discussions and assistanceTorrijos-Morán, L.; Griol Barres, A.; García-Rupérez, J. (2021). Slow light bimodal interferometry in one-dimensional photonic crystal waveguides. Light: Science & Applications. 10(1):16.1-16.12. https://doi.org/10.1038/s41377-020-00460-yS16.116.1210

Ultra-low loss hybrid ITO/Si thermo-optic phase shifter with optimized power consumption

© 2020 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] Typically, materials with large optical losses such as metals are used as microheaters for silicon based thermo-optic phase shifters. Consequently, the heater must be placed far from the waveguide, which could come at the expense of the phase shifter performance. Reducing the gap between the waveguide and the heater allows reducing the power consumption or increasing the switching speed. In this work, we propose an ultra-low loss microheater for thermo-optic tuning by using a CMOS-compatible transparent conducting oxide such as indium tin oxide (ITO) with the aim of drastically reducing the gap. Using finite element method simulations, ITO and Ti based heaters are compared for different cladding configurations and TE and TM polarizations. Furthermore, the proposed ITO based microheaters have also been fabricated using the optimum gap and cladding configuration. Experimental results show power consumption to achieve a pi phase shift of 10 mW and switching time of a few microseconds for a 50 mu m long ITO heater. The obtained results demonstrate the potential of using ITO as an ultra-low loss microheater for high performance silicon thermo-optic tuning and open an alternative way for enabling the large-scale integration of phase shifters required in emerging integrated photonic applications. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementMinisterio de Economía y Competitividad (TEC2016-76849); Generalitat Valenciana (PROMETEO/2019/123); Ministerio de Ciencia, Innovación y Universidades (FPU17/04224).Parra Gómez, J.; Hurtado Montañés, J.; Griol Barres, A.; Sanchis Kilders, P. (2020). Ultra-low loss hybrid ITO/Si thermo-optic phase shifter with optimized power consumption. Optics Express. 28(7):9393-9404. https://doi.org/10.1364/OE.386959S93939404287Komma, J., Schwarz, C., Hofmann, G., Heinert, D., & Nawrodt, R. (2012). Thermo-optic coefficient of silicon at 1550 nm and cryogenic temperatures. Applied Physics Letters, 101(4), 041905. doi:10.1063/1.4738989Sun, J., Timurdogan, E., Yaacobi, A., Hosseini, E. S., & Watts, M. R. (2013). Large-scale nanophotonic phased array. Nature, 493(7431), 195-199. doi:10.1038/nature11727Shen, Y., Harris, N. C., Skirlo, S., Prabhu, M., Baehr-Jones, T., Hochberg, M., … Soljačić, M. (2017). Deep learning with coherent nanophotonic circuits. Nature Photonics, 11(7), 441-446. doi:10.1038/nphoton.2017.93Atabaki, A. H., Moazeni, S., Pavanello, F., Gevorgyan, H., Notaros, J., Alloatti, L., … Ram, R. J. (2018). Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip. Nature, 556(7701), 349-354. doi:10.1038/s41586-018-0028-zPérez, D., Gasulla, I., Crudgington, L., Thomson, D. J., Khokhar, A. Z., Li, K., … Capmany, J. (2017). Multipurpose silicon photonics signal processor core. Nature Communications, 8(1). doi:10.1038/s41467-017-00714-1Sun, P., & Reano, R. M. (2010). Submilliwatt thermo-optic switches using free-standing silicon-on-insulator strip waveguides. Optics Express, 18(8), 8406. doi:10.1364/oe.18.008406Atabaki, A. H., Eftekhar, A. A., Yegnanarayanan, S., & Adibi, A. (2013). Sub-100-nanosecond thermal reconfiguration of silicon photonic devices. Optics Express, 21(13), 15706. doi:10.1364/oe.21.015706Masood, A., Pantouvaki, M., Goossens, D., Lepage, G., Verheyen, P., Van Campenhout, J., … Bogaerts, W. (2014). Fabrication and characterization of CMOS-compatible integrated tungsten heaters for thermo-optic tuning in silicon photonics devices. Optical Materials Express, 4(7), 1383. doi:10.1364/ome.4.001383Rosa, Á., Gutiérrez, A., Brimont, A., Griol, A., & Sanchis, P. (2016). High performace silicon 2x2 optical switch based on a thermo-optically tunable multimode interference coupler and efficient electrodes. Optics Express, 24(1), 191. doi:10.1364/oe.24.000191Jacques, M., Samani, A., El-Fiky, E., Patel, D., Xing, Z., & Plant, D. V. (2019). Optimization of thermo-optic phase-shifter design and mitigation of thermal crosstalk on the SOI platform. Optics Express, 27(8), 10456. doi:10.1364/oe.27.010456Wang, X., & Chiang, K. S. (2019). Polarization-insensitive mode-independent thermo-optic switch based on symmetric waveguide directional coupler. Optics Express, 27(24), 35385. doi:10.1364/oe.27.035385Atabaki, A. H., Shah Hosseini, E., Eftekhar, A. A., Yegnanarayanan, S., & Adibi, A. (2010). Optimization of metallic microheaters for high-speed reconfigurable silicon photonics. Optics Express, 18(17), 18312. doi:10.1364/oe.18.018312Yu, L., Yin, Y., Shi, Y., Dai, D., & He, S. (2016). Thermally tunable silicon photonic microdisk resonator with transparent graphene nanoheaters. Optica, 3(2), 159. doi:10.1364/optica.3.000159Schall, D., Mohsin, M., Sagade, A. A., Otto, M., Chmielak, B., Suckow, S., … Kurz, H. (2016). Infrared transparent graphene heater for silicon photonic integrated circuits. Optics Express, 24(8), 7871. doi:10.1364/oe.24.007871Yan, S., Zhu, X., Frandsen, L. H., Xiao, S., Mortensen, N. A., Dong, J., & Ding, Y. (2017). Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides. Nature Communications, 8(1). doi:10.1038/ncomms14411Xu, Z., Qiu, C., Yang, Y., Zhu, Q., Jiang, X., Zhang, Y., … Su, Y. (2017). Ultra-compact tunable silicon nanobeam cavity with an energy-efficient graphene micro-heater. Optics Express, 25(16), 19479. doi:10.1364/oe.25.019479Lv, J., Yang, Y., Lin, B., Cao, Y., Zhang, Y., Li, S., … Zhang, D. (2019). Graphene-embedded first-order mode polymer Mach–Zender interferometer thermo-optic switch with low power consumption. Optics Letters, 44(18), 4606. doi:10.1364/ol.44.004606Wang, X., Jin, W., Chang, Z., & Chiang, K. S. (2019). Buried graphene electrode heater for a polymer waveguide thermo-optic device. Optics Letters, 44(6), 1480. doi:10.1364/ol.44.001480Lee, D.-J., Kim, H.-M., Kwon, J.-Y., Choi, H., Kim, S.-H., & Kim, K.-B. (2010). Structural and Electrical Properties of Atomic Layer Deposited Al-Doped ZnO Films. Advanced Functional Materials, 21(3), 448-455. doi:10.1002/adfm.201001342Cleary, J. W., Smith, E. M., Leedy, K. D., Grzybowski, G., & Guo, J. (2018). Optical and electrical properties of ultra-thin indium tin oxide nanofilms on silicon for infrared photonics. Optical Materials Express, 8(5), 1231. doi:10.1364/ome.8.001231Ray, S., Banerjee, R., Basu, N., Batabyal, A. K., & Barua, A. K. (1983). Properties of tin doped indium oxide thin films prepared by magnetron sputtering. Journal of Applied Physics, 54(6), 3497-3501. doi:10.1063/1.332415Babicheva, V. E., Kinsey, N., Naik, G. V., Ferrera, M., Lavrinenko, A. V., Shalaev, V. M., & Boltasseva, A. (2013). Towards CMOS-compatible nanophotonics: Ultra-compact modulators using alternative plasmonic materials. Optics Express, 21(22), 27326. doi:10.1364/oe.21.027326Sorger, V. J., Lanzillotti-Kimura, N. D., Ma, R.-M., & Zhang, X. (2012). Ultra-compact silicon nanophotonic modulator with broadband response. Nanophotonics, 1(1), 17-22. doi:10.1515/nanoph-2012-0009Shi, K., Haque, R. R., Zhao, B., Zhao, R., & Lu, Z. (2014). Broadband electro-optical modulator based on transparent conducting oxide. Optics Letters, 39(17), 4978. doi:10.1364/ol.39.004978Hoessbacher, C., Fedoryshyn, Y., Emboras, A., Melikyan, A., Kohl, M., Hillerkuss, D., … Leuthold, J. (2014). The plasmonic memristor: a latching optical switch. Optica, 1(4), 198. doi:10.1364/optica.1.000198Liu, X., Zang, K., Kang, J.-H., Park, J., Harris, J. S., Kik, P. G., & Brongersma, M. L. (2018). Epsilon-Near-Zero Si Slot-Waveguide Modulator. ACS Photonics, 5(11), 4484-4490. doi:10.1021/acsphotonics.8b00945Li, E., Gao, Q., Chen, R. T., & Wang, A. X. (2018). Ultracompact Silicon-Conductive Oxide Nanocavity Modulator with 0.02 Lambda-Cubic Active Volume. Nano Letters, 18(2), 1075-1081. doi:10.1021/acs.nanolett.7b04588Li, E., Gao, Q., Liverman, S., & Wang, A. X. (2018). One-volt silicon photonic crystal nanocavity modulator with indium oxide gate. Optics Letters, 43(18), 4429. doi:10.1364/ol.43.004429Amin, R., Maiti, R., Carfano, C., Ma, Z., Tahersima, M. H., Lilach, Y., … Sorger, V. J. (2018). 0.52 V mm ITO-based Mach-Zehnder modulator in silicon photonics. APL Photonics, 3(12), 126104. doi:10.1063/1.5052635Gao, Q., Li, E., & Wang, A. X. (2018). Ultra-compact and broadband electro-absorption modulator using an epsilon-near-zero conductive oxide. Photonics Research, 6(4), 277. doi:10.1364/prj.6.000277Wood, M. G., Campione, S., Parameswaran, S., Luk, T. S., Wendt, J. R., Serkland, D. K., & Keeler, G. A. (2018). Gigahertz speed operation of epsilon-near-zero silicon photonic modulators. Optica, 5(3), 233. doi:10.1364/optica.5.000233Li, E., Nia, B. A., Zhou, B., & Wang, A. X. (2019). Transparent conductive oxide-gated silicon microring with extreme resonance wavelength tunability. 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Thermal effect analysis of silicon microring optical switch for on-chip interconnect. Journal of Semiconductors, 38(10), 104004. doi:10.1088/1674-4926/38/10/10400

Photonic Frequency Conversion of OFDM Microwave Signals in a Wavelength-Scale Optomechanical Cavity

[EN] Optomechanical (OM) cavities enable coupling of near-infrared light and GHz-frequency acoustic waves in wavelength-scale volumes. When driven in the phonon lasing regime, an OM cavity can perform simultaneously as a nonlinear mixer and a local oscillator¿at integer multiples of the mechanical resonance frequency¿in the optical domain. In this work, this property is used to demonstrate all-optical frequency down- and up-conversion of MHz-bandwidth orthogonal frequency division multiplexed signals compliant with the IEEE 802.16e WiMAX wireless standard at microwave frequencies. To this end, a silicon OM crystal cavity (OMCC), supporting a breathing-like mechanical resonance at fm ¿3.9 GHz and having a foot-print ¿ 10 um^2, which yields frequency conversion efficiencies better than ¿17 dB in both down- and up-conversion processes at mW-scale driving power, is employed. This work paves the way toward the application of OMCCs in low-power all-photonic processing of digitally modulated microwave signals in miniaturized silicon photonics chips.The authors acknowledge funding from the H2020 Future and Emerging Technologies program (projects PHENOMEN 713450 and SIOMO 945915); the Spanish State Research Agency (PGC2018-094490-BC21, PID2019-106163RJ-I00/AEI/10.13039/501100011033 MULTICORE+ and MCIU/AEI/FEDER UE RTI2018-101296-B-I00 MULTI-BEAM5G); Generalitat Valenciana (PPC/2021/042, BEST/2020/178, PROMETEO/2019/123 and IDIFEDER/2018/033); and the UPV Programa de Ayudas de Investigacion y Desarrollo (PAID-01-16).Mercadé-Morales, L.; Morant, M.; Griol Barres, A.; Llorente, R.; Martínez, A. (2021). Photonic Frequency Conversion of OFDM Microwave Signals in a Wavelength-Scale Optomechanical Cavity. Laser & Photonics Review. 15(11):1-8. https://doi.org/10.1002/lpor.20210017518151

Experimental observation of higher-order anapoles in individual silicon disks under in-plane illumination

[EN] Anapole states¿characterized by a strong suppression of far-field scattering¿naturally arise in high-index nanoparticles as a result of the interference between certain multipolar moments. Recently, the first-order electric anapole, resulting from the interference between the electric and toroidal dipoles, was characterized under in-plane illumination as required in on-chip photonics. Here, we go a step further and report on the observation of higher-order (magnetic and second-order electric) anapole states in individual silicon disks under in-plane illumination. To do so, we increase the disk dimensions (radius and thickness) so that such anapoles occur at telecom wavelengths. Experiments show dips in the far-field scattering perpendicular to the disk plane at the expected wavelengths and the selected polarizations, which we interpret as a signature of high-order anapoles. Some differences between normal and in-plane excitation are discussed, in particular, the non-cancelation of the sum of the Cartesian electric and toroidal moments for in-plane incidence. Our results pave the way toward the use of different anapole states in photonic integrated circuits either on silicon or other high-index dielectric materials.This work was supported by Generalitat Valenciana under Grant No. GRISOLIAP/2018/164, the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through the International Research Training Group (IRTG) 2675 "Meta-ACTIVE," Project No. 437527638, and Generalitat Valenciana (Grant Nos. PROMETEO/2019/123, IDIFEDER/2020/041, and IDIFEDER/2021/061).Díaz-Escobar, E.; Barreda-Gómez, ÁI.; Griol Barres, A.; Martínez, A. (2022). Experimental observation of higher-order anapoles in individual silicon disks under in-plane illumination. Applied Physics Letters. 121(20):1-8. https://doi.org/10.1063/5.0108438181212

On-Chip Optimal Stokes Nanopolarimetry Based on Spin-Orbit Interaction of Light

[EN] Full measurement of the polarization of light at the nanoscale is expected to be crucial in many scientific and technological disciplines. Ideally, such measurements will require miniaturized Stokes polarimeters able to determine polarization nondestructively, locally, and in real time. For maximum robustness in measurement, the polarimeters should also operate optimally. Recent approaches making use of plasmonic nanostructures or metasurfaces are not able to fulfill all these requirements simultaneously. Here, we propose and demonstrate a method for subwavelength-footprint Stokes nanopolarimetry based on spin-orbit interaction of light. The method, which basically consists on a subwavelength scatterer coupled to a (set of) multimode waveguide(s), can fully determine the state of polarization satisfying all the previous features. Remarkably, the nanopolarimetry technique can operate optimally (we design a nanopolarimeter whose polarization basis spans 99.7% of the maximum tetrahedron volume inside the Poincaré sphere) over a broad bandwidth. Although here experimentally demonstrated on a silicon chip at telecom wavelengths, spin-orbit interaction-based nanopolarimetry is a universal concept to be applied in any wavelength regime or technological platform.A.M. acknowledges support from the Spanish Ministry of Economy and Competiveness (MINECO) under grant TEC2014-51902-C2-1-R and the Valencian Conselleria d'Educacion, Cultura i Esport under grant PROMETEOII/2014/034. FJ.R.-F. acknowledges support from the European Research Council under project ERC-2016-STG-714151-PSINFONI. A.E.-S. acknowledges support from the Spanish Ministry of Economy and Competiveness (MINECO) under grant BES-2015-073146.Espinosa Soria, A.; Rodríguez Fortuño, FJ.; Griol Barres, A.; Martínez Abietar, AJ. (2017). On-Chip Optimal Stokes Nanopolarimetry Based on Spin-Orbit Interaction of Light. Nano Letters. 17(5):3139-3144. https://doi.org/10.1021/acs.nanolett.7b00564S3139314417

Performance improvement of a silicon nitride ring resonator biosensor operated in the TM mode at 1310 nm

[EN] Silicon-based ring resonators have been demonstrated to be a key element to build lab-on-chip devices due to their ability to perform as label-free photonic sensors. In this work, we demonstrate photonic biosensing using silicon nitride ring resonators operated in the TM mode around 1310 nm wavelengths. Our results show that operating the devices using the TM mode results in an increased sensitivity in comparison with the typically used TE mode, while working at 1310 nm wavelengths compared to 1550 nm contributes to an increased quality factor. As a result, a reduction in the intrinsic limit of detection is achieved, indicating the suitability of TM modes in the 1310 nm regime for biosensing using integrated photonics.Generalitat Valenciana (IDIFEDER/2018/033, IDIFEDER/2021/061, PROMETEO/2019/123) ; Ministerio de Ciencia, Innovacion y Universidades (ICTS-2017-28-UPV-9) ; Horizon 2020 Framework Programme (958855)Castello-Pedero, L.; Gómez-Gómez, MI.; García-Rupérez, J.; Griol Barres, A.; Martínez, A. (2021). Performance improvement of a silicon nitride ring resonator biosensor operated in the TM mode at 1310 nm. Biomedical Optics Express. 12(11):7244-7260. https://doi.org/10.1364/BOE.437823S72447260121

High signal-to-noise ratio ultra-compact lab-on-a-chip microflow cytometer enabled by silicon optical antennas

[EN] We experimentally demonstrate an all-silicon nanoantenna-based micro-optofluidic cytometer showing a combination of high signal-to-noise ratio (SNR) > 14 dB and ultra-compact size. Thanks to the ultra-high directivity of the antennas (>150), which enables a state-of-the-art sub-micron resolution, we are able to avoid the use of the bulky devices typically employed to collimate light on chip (such as lenses or fibers). The nm-scale antenna cross section allows a dramatic reduction of the optical system footprint, from the mm-scale of previous approaches to a few mu m(2), yielding a notable reduction in the fabrication costs. This scheme paves the way to ultra-compact lab-on-a-chip devices that may enable new applications with potential impact on all branches of biological and health science.Funding from grant TEC2015-63838-C3-1-R OPTONANOSENS (MINECO/FEDER, UE) is acknowledged. C. G.-M. acknowledges support from project TEC2015-73581-JIN PHUTURE (AEI/FEDER, UE). This work was also supported by the EU-funded projects FP7-ICT PHOXTROT (No. 318240), the EU-funded H2020-FET-HPC EXANEST (No. 671553) and the Generalitat Valenciana's PROMETEO grant NANOMET PLUS (PROMETEO II/2014/34).Lechago-Buendia, S.; García Meca, C.; Sánchez Losilla, N.; Griol Barres, A.; Martí Sendra, J. (2018). High signal-to-noise ratio ultra-compact lab-on-a-chip microflow cytometer enabled by silicon optical antennas. Optics Express. 26(20):25645-25656. https://doi.org/10.1364/OE.26.02564525645256562620Redding, B., Liew, S. F., Sarma, R., & Cao, H. (2013). Compact spectrometer based on a disordered photonic chip. Nature Photonics, 7(9), 746-751. doi:10.1038/nphoton.2013.190Malinauskas, M., Žukauskas, A., Hasegawa, S., Hayasaki, Y., Mizeikis, V., Buividas, R., & Juodkazis, S. (2016). Ultrafast laser processing of materials: from science to industry. Light: Science & Applications, 5(8), e16133-e16133. doi:10.1038/lsa.2016.133Fan, X., & White, I. M. (2011). 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Micro flow cytometer with self-aligned 3D hydrodynamic focusing. Biomedical Optics Express, 6(1), 54. doi:10.1364/boe.6.000054Etcheverry, S., Faridi, A., Ramachandraiah, H., Kumar, T., Margulis, W., Laurell, F., & Russom, A. (2017). High performance micro-flow cytometer based on optical fibres. Scientific Reports, 7(1). doi:10.1038/s41598-017-05843-7Kosako, T., Kadoya, Y., & Hofmann, H. F. (2010). Directional control of light by a nano-optical Yagi–Uda antenna. Nature Photonics, 4(5), 312-315. doi:10.1038/nphoton.2010.34Taillaert, D., Van Laere, F., Ayre, M., Bogaerts, W., Van Thourhout, D., Bienstman, P., & Baets, R. (2006). Grating Couplers for Coupling between Optical Fibers and Nanophotonic Waveguides. Japanese Journal of Applied Physics, 45(8A), 6071-6077. doi:10.1143/jjap.45.6071Potcoava, M. C., Futia, G. L., Aughenbaugh, J., Schlaepfer, I. R., & Gibson, E. A. (2014). 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Bimodal grating coupler design on SOI technology for mode division multiplexing at 1550 nm

© 2018 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] In this paper, we evaluate by means of simulation and experimentally the simultaneous coupling of the LP01x-LP11ax fiber modes and the TE0-TE1 nanophotonic SOI waveguide modes using a grating coupler for a two-mode fiber at 1550 nm. Both the grating width (ranging from 10 mu m to 15 mu m) and the grating vertical profile have been considered in the design procedure. The optimum design (14 mu m width and 609 nm grating period) has been selected in terms of coupling efficiency (both LP01x-TE0 and LP11ax-TE1), compactness and tolerance to lateral misalignments between fiber and coupler. The LP01x-TE0 and LP11ax-TE1 modes achieved coupling efficiencies of 49% and 45%, respectively. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing AgreementMinisterio de Economia y Competitividad (MINECO/FEDER) (TEC2015-70858-C2-1-R, RTC-2014-2232-3)García-Rodríguez, D.; Corral, JL.; Griol Barres, A.; Llorente, R. (2018). Bimodal grating coupler design on SOI technology for mode division multiplexing at 1550 nm. Optics Express. 26(15):19445-19455. https://doi.org/10.1364/OE.26.019445S19445194552615Richardson, D. J. (2016). New optical fibres for high-capacity optical communications. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 374(2062), 20140441. doi:10.1098/rsta.2014.0441Kasahara, M., Saitoh, K., Sakamoto, T., Hanzawa, N., Matsui, T., Tsujikawa, K., … Koshiba, M. (2013). Design of Few-Mode Fibers for Mode-Division Multiplexing Transmission. IEEE Photonics Journal, 5(6), 7201207-7201207. doi:10.1109/jphot.2013.2292365Chen, H., Sleiffer, V., Snyder, B., Kuschnerov, M., van Uden, R., Jung, Y., … Koonen, T. (2013). Demonstration of a Photonic Integrated Mode Coupler With MDM and WDM Transmission. IEEE Photonics Technology Letters, 25(21), 2039-2042. doi:10.1109/lpt.2013.2280669Sun, C., Yu, Y., Ye, M., Chen, G., & Zhang, X. (2016). An ultra-low crosstalk and broadband two-mode (de)multiplexer based on adiabatic couplers. Scientific Reports, 6(1). doi:10.1038/srep38494Xing, J., Li, Z., Xiao, X., Yu, J., & Yu, Y. (2013). Two-mode multiplexer and demultiplexer based on adiabatic couplers. Optics Letters, 38(17), 3468. doi:10.1364/ol.38.003468Garcia-Rodriguez, D., Corral, J. L., Griol, A., & Llorente, R. (2017). Dimensional variation tolerant mode converter/multiplexer fabricated in SOI technology for two-mode transmission at 1550  nm. Optics Letters, 42(7), 1221. doi:10.1364/ol.42.001221Garcia-Rodriguez, D., Corral, J. L., & Llorente, R. (2017). Mode Conversion for Mode Division Multiplexing at 850 nm in Standard SMF. IEEE Photonics Technology Letters, 29(11), 929-932. doi:10.1109/lpt.2017.2694605Zhang, Z., Hu, X., & Wang, J. (2015). On-chip optical mode exchange using tapered directional coupler. Scientific Reports, 5(1). doi:10.1038/srep16072Ding, Y., Xu, J., Da Ros, F., Huang, B., Ou, H., & Peucheret, C. (2013). On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer. Optics Express, 21(8), 10376. doi:10.1364/oe.21.010376Zanzi, A., Brimont, A., Griol, A., Sanchis, P., & Marti, J. (2016). Compact and low-loss asymmetrical multimode interference splitter for power monitoring applications. Optics Letters, 41(2), 227. doi:10.1364/ol.41.000227Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2013). Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission. Optics Express, 21(22), 25752. doi:10.1364/oe.21.025752Lai, Y., Yu, Y., Fu, S., Xu, J., Shum, P. P., & Zhang, X. (2017). Efficient spot size converter for higher-order mode fiber-chip coupling. Optics Letters, 42(18), 3702. doi:10.1364/ol.42.003702Hatori, N., Shimizu, T., Okano, M., Ishizaka, M., Yamamoto, T., Urino, Y., … Arakawa, Y. (2014). A Hybrid Integrated Light Source on a Silicon Platform Using a Trident Spot-Size Converter. Journal of Lightwave Technology, 32(7), 1329-1336. doi:10.1109/jlt.2014.2304305Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2014). Mode multi/demultiplexing with parallel waveguide for mode division multiplexed transmission. Optics Express, 22(24), 29321. doi:10.1364/oe.22.029321Dai, D., & Mao, M. (2015). Mode converter based on an inverse taper for multimode silicon nanophotonic integrated circuits. Optics Express, 23(22), 28376. doi:10.1364/oe.23.028376Taillaert, D., Van Laere, F., Ayre, M., Bogaerts, W., Van Thourhout, D., Bienstman, P., & Baets, R. (2006). Grating Couplers for Coupling between Optical Fibers and Nanophotonic Waveguides. Japanese Journal of Applied Physics, 45(8A), 6071-6077. doi:10.1143/jjap.45.6071Lardenois, S., Pascal, D., Vivien, L., Cassan, E., Laval, S., Orobtchouk, R., … Mollard, L. (2003). Low-loss submicrometer silicon-on-insulator rib waveguides and corner mirrors. Optics Letters, 28(13), 1150. doi:10.1364/ol.28.001150Orobtchouk, R., Layadi, A., Gualous, H., Pascal, D., Koster, A., & Laval, S. (2000). High-efficiency light coupling in a submicrometric silicon-on-insulator waveguide. Applied Optics, 39(31), 5773. doi:10.1364/ao.39.005773Wohlfeil, B., Rademacher, G., Stamatiadis, C., Voigt, K., Zimmermann, L., & Petermann, K. (2016). A Two-Dimensional Fiber Grating Coupler on SOI for Mode Division Multiplexing. IEEE Photonics Technology Letters, 28(11), 1241-1244. doi:10.1109/lpt.2016.2514712Koonen, A. M. J., Haoshuo Chen, van den Boom, H. P. A., & Raz, O. (2012). Silicon Photonic Integrated Mode Multiplexer and Demultiplexer. IEEE Photonics Technology Letters, 24(21), 1961-1964. doi:10.1109/lpt.2012.2219304Ding, Y., Ou, H., Xu, J., & Peucheret, C. (2013). Silicon Photonic Integrated Circuit Mode Multiplexer. IEEE Photonics Technology Letters, 25(7), 648-651. doi:10.1109/lpt.2013.2247394Galan, J. V., Sanchis, P., Blasco, J., & Marti, J. (2008). Study of High Efficiency Grating Couplers for Silicon-Based Horizontal Slot Waveguides. IEEE Photonics Technology Letters, 20(12), 985-987. doi:10.1109/lpt.2008.923546Roelkens, G., Van Thourhout, D., & Baets, R. (2006). High efficiency Silicon-on-Insulator grating coupler based on a poly-Silicon overlay. Optics Express, 14(24), 11622. doi:10.1364/oe.14.01162

Ultra-compact optical switches using slow light bimodal silicon waveguides

[EN] Switches are essential components in several optical applications, in which reduced footprints are highly desirable for mass production of densely integrated circuits at low cost. However, most conventional solutions rely on making long switching structures, thus increasing the final device size. Here, we propose and experimentally demonstrate an ultra-compact 2x2 optical switch based on slow-light-enhanced bimodal interferometry in one-dimensional silicon photonic crystals. By properly designing the band structure, the device exhibits a large group index contrast between the fundamental even mode and a higher order odd mode for TE polarization. Thereby, highly dispersive and broadband bimodal regions for high-performance operation are engineered by exploiting the different symmetry of the modes. Two configurations are considered in the experiments to analyze the dimensions influence on the switching efficiency. As a result, a photonic switch based on a bimodal single-channel interferometer with a footprint of only 63 mu m(2), a power consumption of 19.5 mW and a crosstalk of 15 dB is demonstrated for thermo-optic tunability.This work was supported in part by Generalitat Valenciana under Grants AVANTI/2019/123 and ACIF/2019/009, in part by the Spanish Ministerio de Ciencia e Innovacion through PID2019-106965RBC21 and PID2019-111460GB-I00 projects, and in part by the European Union through the operational program of the European Regional Development Fund (FEDER) of the Valencia Regional Government 2014-2020Torrijos-Morán, L.; Brimont, ACJ.; Griol Barres, A.; Sanchis Kilders, P.; García-Rupérez, J. (2021). Ultra-compact optical switches using slow light bimodal silicon waveguides. Journal of Lightwave Technology. 39(11):3495-3501. https://doi.org/10.1109/JLT.2021.3066479S34953501391

Dimensional variation tolerant mode converter/multiplexer fabricated in SOI technology for two-mode transmission at 1550 nm

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.42.001221. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawThe use of an integrated asymmetrical directional coupler for two-mode transmission at 1550 nm is analyzed. The design is based on silicon-on-insulator (SOI) technology and permits mode conversion and mode multiplexing/demultiplexing. In the nominal design, mode conversion and mode (de) multiplexing are achieved with 97% efficiency and a 23.4 dB crosstalk level in the 1540-1560 nm band using a 0.1 mu m gap. The dimension tolerance of the SOI process has been taken into account in the selection of the optimum design, and the coupling efficiency would remain above 82.3% (corresponding to 0.8 dB excess loss) with 3 sigma accuracy. A 90% efficiency has been experimentally obtained.Ministerio de Economia y Competitividad (MINECO) (TEC2015-70858-C2-1-R, RTC-2014-2232-3).García-Rodríguez, D.; Corral, JL.; Griol Barres, A.; Llorente Sáez, R. (2017). Dimensional variation tolerant mode converter/multiplexer fabricated in SOI technology for two-mode transmission at 1550 nm. Optics Letters. 42(7):1221-1224. doi:10.1364/OL.42.001221S12211224427Greenberg, M., & Orenstein, M. (2005). Multimode add-drop multiplexing by adiabatic linearly tapered coupling. Optics Express, 13(23), 9381. doi:10.1364/opex.13.009381Uematsu, T., Ishizaka, Y., Kawaguchi, Y., Saitoh, K., & Koshiba, M. (2012). Design of a Compact Two-Mode Multi/Demultiplexer Consisting of Multimode Interference Waveguides and a Wavelength-Insensitive Phase Shifter for Mode-Division Multiplexing Transmission. Journal of Lightwave Technology, 30(15), 2421-2426. doi:10.1109/jlt.2012.2199961Ding, Y., Xu, J., Da Ros, F., Huang, B., Ou, H., & Peucheret, C. (2013). On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer. Optics Express, 21(8), 10376. doi:10.1364/oe.21.010376Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2014). Mode multi/demultiplexing with parallel waveguide for mode division multiplexed transmission. Optics Express, 22(24), 29321. doi:10.1364/oe.22.029321Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2013). Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission. Optics Express, 21(22), 25752. doi:10.1364/oe.21.025752Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Uematsu, T., & Yamamoto, F. (2015). PLC-Based Four-Mode Multi/Demultiplexer With LP11 Mode Rotator on One Chip. Journal of Lightwave Technology, 33(6), 1161-1165. doi:10.1109/jlt.2014.2378281Wang, J., He, S., & Dai, D. (2014). On-chip silicon 8-channel hybrid (de)multiplexer enabling simultaneous mode- and polarization-division-multiplexing. Laser & Photonics Reviews, 8(2), L18-L22. doi:10.1002/lpor.201300157Dai, D., Wang, J., & Shi, Y. (2013). Silicon mode (de)multiplexer enabling high capacity photonic networks-on-chip with a single-wavelength-carrier light. Optics Letters, 38(9), 1422. doi:10.1364/ol.38.001422Corral, J. L., Garcia-Rodriguez, D., & Llorente, R. (2016). Mode-Selective Couplers for Two-Mode Transmission at 850 nm in Standard SMF. IEEE Photonics Technology Letters, 28(4), 425-428. doi:10.1109/lpt.2015.2497080Xu, K. (2014). Corrections to «On the Design and Optimization of Three-Terminal Light-Emitting Device in Silicon CMOS Technology» [Jul/Aug 14 8201208]. IEEE Journal of Selected Topics in Quantum Electronics, 20(4), 422-422. doi:10.1109/jstqe.2014.2318271Grigorescu, A. E., van der Krogt, M. C., & Hagen, C. W. (2007). Sub-10-nm structures written in ultra-thin HSQ resist layers using electron-beam lithography. Advances in Resist Materials and Processing Technology XXIV. doi:10.1117/12.72585