2019
|
A Xomalis, Y Jung, I Demirtzioglou, C Lacava, E Plum, D J Richardson, P Petropoulos, N I Zheludev Nonlinear control of coherent absorption and its optical signal processing applications Journal Article APL Photonics, 4 (10), 2019. Abstract | Links | Tags: nonlinear optics, wavelength conversion, wavelength converter @article{Xomalis2019,
title = {Nonlinear control of coherent absorption and its optical signal processing applications},
author = {A Xomalis and Y Jung and I Demirtzioglou and C Lacava and E Plum and D J Richardson and P Petropoulos and N I Zheludev},
doi = {10.1063/1.5123547},
year = {2019},
date = {2019-01-01},
journal = {APL Photonics},
volume = {4},
number = {10},
abstract = {All-optical data processing continues to attract significant interest as a way to overcome the electronic signal processing bottleneck of fiber telecommunication networks. Nonlinear optical devices such as limiters and saturable absorbers rely on intensity-dependent attenuation of light. However, making such devices using intensity-dependent multiphoton dissipation processes is an issue as these make complete absorption and transmission impossible. Here, we show that nonlinear phase retardation in an optical fiber can control the dissipation of coherent light waves interacting on a thin plasmonic absorber from total absorption to perfect transmission. The fiber's instantaneous Kerr nonlinearity and the femtosecond coherent absorption time scale make this approach ultrafast. We report proof-of-principle demonstrations of all-optical intensity discrimination, power limiting, pulse restoration, pulse splitting, and signal transfer between carrier wavelengths within a fiber circuit. Our results indicate that nonlinear control of coherent absorption can imitate and outperform saturable and multiphoton absorption in terms of bandwidth and contrast.},
keywords = {nonlinear optics, wavelength conversion, wavelength converter},
pubstate = {published},
tppubtype = {article}
}
All-optical data processing continues to attract significant interest as a way to overcome the electronic signal processing bottleneck of fiber telecommunication networks. Nonlinear optical devices such as limiters and saturable absorbers rely on intensity-dependent attenuation of light. However, making such devices using intensity-dependent multiphoton dissipation processes is an issue as these make complete absorption and transmission impossible. Here, we show that nonlinear phase retardation in an optical fiber can control the dissipation of coherent light waves interacting on a thin plasmonic absorber from total absorption to perfect transmission. The fiber's instantaneous Kerr nonlinearity and the femtosecond coherent absorption time scale make this approach ultrafast. We report proof-of-principle demonstrations of all-optical intensity discrimination, power limiting, pulse restoration, pulse splitting, and signal transfer between carrier wavelengths within a fiber circuit. Our results indicate that nonlinear control of coherent absorption can imitate and outperform saturable and multiphoton absorption in terms of bandwidth and contrast. |
A Xomalis, I Demirtzioglou, Y Jung, E Plum, C Lacava, P Petropoulos, D J Richardson, N I Zheludev Cryptography in coherent optical information networks using dissipative metamaterial gates Journal Article APL Photonics, 4 (4), 2019. Abstract | Links | Tags: nonlinear optics, nonlinear waveguides @article{Xomalis2019a,
title = {Cryptography in coherent optical information networks using dissipative metamaterial gates},
author = {A Xomalis and I Demirtzioglou and Y Jung and E Plum and C Lacava and P Petropoulos and D J Richardson and N I Zheludev},
doi = {10.1063/1.5092216},
year = {2019},
date = {2019-01-01},
journal = {APL Photonics},
volume = {4},
number = {4},
abstract = {All-optical encryption of information in fibre telecommunication networks offers lower complexity and far higher data rates than electronic encryption can deliver. However, existing optical layer encryption methods, which are compatible with keys of unlimited length, are based on nonlinear processes that require intense optical fields. Here, we introduce an optical layer secure communication protocol that does not rely on nonlinear optical processes but instead uses energy redistribution of coherent optical waves interacting on a plasmonic metamaterial absorber. We implement the protocol in a telecommunication optical fibre information network, where signal and key distribution lines use a common coherent information carrier. We investigate and demonstrate different encryption modes, including a scheme providing perfect secrecy. All-optical cryptography, as demonstrated here, exploits signal processing mechanisms that can satisfy optical telecom data rate requirements in any current or next-generation frequency band with bandwidth exceeding 100 THz and a switching energy of a few photons per bit. This is the first demonstration of an optical telecommunications application of metamaterial technology.},
keywords = {nonlinear optics, nonlinear waveguides},
pubstate = {published},
tppubtype = {article}
}
All-optical encryption of information in fibre telecommunication networks offers lower complexity and far higher data rates than electronic encryption can deliver. However, existing optical layer encryption methods, which are compatible with keys of unlimited length, are based on nonlinear processes that require intense optical fields. Here, we introduce an optical layer secure communication protocol that does not rely on nonlinear optical processes but instead uses energy redistribution of coherent optical waves interacting on a plasmonic metamaterial absorber. We implement the protocol in a telecommunication optical fibre information network, where signal and key distribution lines use a common coherent information carrier. We investigate and demonstrate different encryption modes, including a scheme providing perfect secrecy. All-optical cryptography, as demonstrated here, exploits signal processing mechanisms that can satisfy optical telecom data rate requirements in any current or next-generation frequency band with bandwidth exceeding 100 THz and a switching energy of a few photons per bit. This is the first demonstration of an optical telecommunications application of metamaterial technology. |
2017
|
T Domínguez Bucio, A Z Khokhar, C Lacava, S Stankovic, G Z Mashanovich, P Petropoulos, F Y Gardes Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications Journal Article Journal of Physics D: Applied Physics, 50 (2), 2017. Abstract | Links | Tags: nonlinear optics, nonlinear waveguides, silicon nitride, Silicon photonics, silicon-rich @article{DominguezBucio2017,
title = {Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications},
author = {T {Domínguez Bucio} and A Z Khokhar and C Lacava and S Stankovic and G Z Mashanovich and P Petropoulos and F Y Gardes},
doi = {10.1088/1361-6463/50/2/025106},
year = {2017},
date = {2017-01-01},
journal = {Journal of Physics D: Applied Physics},
volume = {50},
number = {2},
abstract = {SiNx layers intended for photonic applications are typically fabricated using LPCVD and PECVD. These techniques rely on high-temperature processing (textgreater400 °C) to obtain low propagation losses. An alternative version of PECVD SiNx layers deposited at temperatures below 400 °C with a recipe that does not use ammonia (NH3-free PECVD) was previously demonstrated to be a good option to fabricate strip waveguides with propagation losses textless3 dB cm-1. We have conducted a systematic investigation of the influence of the deposition parameters on the material and optical properties of NH3-free PECVD SiNx layers fabricated at 350 °C using a design of experiments methodology. In particular, this paper discusses the effect of the SiH4 flow, RF power, chamber pressure and substrate on the structure, uniformity, roughness, deposition rate, refractive index, chemical composition, bond structure and H content of NH3-free PECVD SiNx layers. The results show that the properties and the propagation losses of the studied SiNx layers depend entirely on their compositional N/Si ratio, which is in fact the only parameter that can be directly tuned using the deposition parameters along with the film uniformity and deposition rate. These observations provide the means to optimise the propagation losses of the layers for photonic applications through the deposition parameters. In fact, we have been able to fabricate SiNx waveguides with H content textless20%, good uniformity and propagation losses of 1.5 dB cm-1 at 1550 nm and textless1 dB cm-1 at 1310 nm. As a result, this study can potentially help optimise the properties of the studied SiNx layers for different applications.},
keywords = {nonlinear optics, nonlinear waveguides, silicon nitride, Silicon photonics, silicon-rich},
pubstate = {published},
tppubtype = {article}
}
SiNx layers intended for photonic applications are typically fabricated using LPCVD and PECVD. These techniques rely on high-temperature processing (textgreater400 °C) to obtain low propagation losses. An alternative version of PECVD SiNx layers deposited at temperatures below 400 °C with a recipe that does not use ammonia (NH3-free PECVD) was previously demonstrated to be a good option to fabricate strip waveguides with propagation losses textless3 dB cm-1. We have conducted a systematic investigation of the influence of the deposition parameters on the material and optical properties of NH3-free PECVD SiNx layers fabricated at 350 °C using a design of experiments methodology. In particular, this paper discusses the effect of the SiH4 flow, RF power, chamber pressure and substrate on the structure, uniformity, roughness, deposition rate, refractive index, chemical composition, bond structure and H content of NH3-free PECVD SiNx layers. The results show that the properties and the propagation losses of the studied SiNx layers depend entirely on their compositional N/Si ratio, which is in fact the only parameter that can be directly tuned using the deposition parameters along with the film uniformity and deposition rate. These observations provide the means to optimise the propagation losses of the layers for photonic applications through the deposition parameters. In fact, we have been able to fabricate SiNx waveguides with H content textless20%, good uniformity and propagation losses of 1.5 dB cm-1 at 1550 nm and textless1 dB cm-1 at 1310 nm. As a result, this study can potentially help optimise the properties of the studied SiNx layers for different applications. |
M A Ettabib, C Lacava, Z Liu, A Bogris, A Kapsalis, M Brun, P Labeye, S Nicoletti, D Syvridis, D J Richardson, D J Richardson, P Petropoulos Wavelength conversion of complex modulation formats in a compact SiGe waveguide Journal Article Optics Express, 25 (4), pp. 3252–3258, 2017. Abstract | Links | Tags: frequency conversion, frequency generation, integrated optics, nonlinear optics, Silicon photonics, wavelength conversion @article{Ettabib2017,
title = {Wavelength conversion of complex modulation formats in a compact SiGe waveguide},
author = {M A Ettabib and C Lacava and Z Liu and A Bogris and A Kapsalis and M Brun and P Labeye and S Nicoletti and D Syvridis and D J Richardson and D J Richardson and P Petropoulos},
doi = {10.1364/OE.25.003252},
year = {2017},
date = {2017-01-01},
journal = {Optics Express},
volume = {25},
number = {4},
pages = {3252--3258},
abstract = {We report a nonlinear signal processing system based on a SiGe waveguide suitable for high spectral efficiency data signals. Four-wave-mixing (FWM)-based wavelength conversion of 10-Gbaud 16-Quadrature amplitude modulated (QAM) and 64-QAM signals is demonstrated with less than -10-dB conversion efficiency (CE), 36-dB idler optical signal-to-noise ratio (OSNR), negligible bit error ratio (BER) penalty and a 3-dB conversion bandwidth exceeding 30nm. The SiGe device was CW-pumped and operated in a passive scheme without giving rise to any two-photon absorption (TPA) effects.},
keywords = {frequency conversion, frequency generation, integrated optics, nonlinear optics, Silicon photonics, wavelength conversion},
pubstate = {published},
tppubtype = {article}
}
We report a nonlinear signal processing system based on a SiGe waveguide suitable for high spectral efficiency data signals. Four-wave-mixing (FWM)-based wavelength conversion of 10-Gbaud 16-Quadrature amplitude modulated (QAM) and 64-QAM signals is demonstrated with less than -10-dB conversion efficiency (CE), 36-dB idler optical signal-to-noise ratio (OSNR), negligible bit error ratio (BER) penalty and a 3-dB conversion bandwidth exceeding 30nm. The SiGe device was CW-pumped and operated in a passive scheme without giving rise to any two-photon absorption (TPA) effects. |
C Lacava, S Stankovic, A Khokhar, T Bucio, F Gardes, G Reed, D Richardson, P Petropoulos Si-rich Silicon Nitride for Nonlinear Signal Processing Applications Journal Article Scientific Reports, 7 (1), 2017. Abstract | Links | Tags: nonlinear optics, silicon nitride, Silicon photonics, silicon-rich @article{Lacava2017,
title = {Si-rich Silicon Nitride for Nonlinear Signal Processing Applications},
author = {C Lacava and S Stankovic and A Khokhar and T Bucio and F Gardes and G Reed and D Richardson and P Petropoulos},
doi = {10.1038/s41598-017-00062-6},
year = {2017},
date = {2017-01-01},
journal = {Scientific Reports},
volume = {7},
number = {1},
abstract = {Nonlinear silicon photonic devices have attracted considerable attention thanks to their ability to show large third-order nonlinear effects at moderate power levels allowing for all-optical signal processing functionalities in miniaturized components. Although significant efforts have been made and many nonlinear optical functions have already been demonstrated in this platform, the performance of nonlinear silicon photonic devices remains fundamentally limited at the telecom wavelength region due to the two photon absorption (TPA) and related effects. In this work, we propose an alternative CMOS-compatible platform, based on silicon-rich silicon nitride that can overcome this limitation. By carefully selecting the material deposition parameters, we show that both of the device linear and nonlinear properties can be tuned in order to exhibit the desired behaviour at the selected wavelength region. A rigorous and systematic fabrication and characterization campaign of different material compositions is presented, enabling us to demonstrate TPA-free CMOS-compatible waveguides with low linear loss (∼1.5 dB/cm) and enhanced Kerr nonlinear response (Re$gamma$ = 16 Wm-1). Thanks to these properties, our nonlinear waveguides are able to produce a $pi$ nonlinear phase shift, paving the way for the development of practical devices for future optical communication applications.},
keywords = {nonlinear optics, silicon nitride, Silicon photonics, silicon-rich},
pubstate = {published},
tppubtype = {article}
}
Nonlinear silicon photonic devices have attracted considerable attention thanks to their ability to show large third-order nonlinear effects at moderate power levels allowing for all-optical signal processing functionalities in miniaturized components. Although significant efforts have been made and many nonlinear optical functions have already been demonstrated in this platform, the performance of nonlinear silicon photonic devices remains fundamentally limited at the telecom wavelength region due to the two photon absorption (TPA) and related effects. In this work, we propose an alternative CMOS-compatible platform, based on silicon-rich silicon nitride that can overcome this limitation. By carefully selecting the material deposition parameters, we show that both of the device linear and nonlinear properties can be tuned in order to exhibit the desired behaviour at the selected wavelength region. A rigorous and systematic fabrication and characterization campaign of different material compositions is presented, enabling us to demonstrate TPA-free CMOS-compatible waveguides with low linear loss (∼1.5 dB/cm) and enhanced Kerr nonlinear response (Re$gamma$ = 16 Wm-1). Thanks to these properties, our nonlinear waveguides are able to produce a $pi$ nonlinear phase shift, paving the way for the development of practical devices for future optical communication applications. |
2016
|
C Lacava, M A Ettabib, I Cristiani, J M Fedeli, D J Richardson, P Petropoulos Ultra-Compact Amorphous Silicon Waveguide for Wavelength Conversion Journal Article IEEE Photonics Technology Letters, 28 (4), pp. 410–413, 2016. Abstract | Links | Tags: BSPK, nonlinear optics, QPSK, Silicon photonics, wavelength converter @article{Lacava2016,
title = {Ultra-Compact Amorphous Silicon Waveguide for Wavelength Conversion},
author = {C Lacava and M A Ettabib and I Cristiani and J M Fedeli and D J Richardson and P Petropoulos},
doi = {10.1109/LPT.2015.2496758},
year = {2016},
date = {2016-01-01},
journal = {IEEE Photonics Technology Letters},
volume = {28},
number = {4},
pages = {410--413},
abstract = {In this letter, we demonstrate, for the first time, successful four wave mixing (FWM)-based wavelength conversion of binary phase shift keyed (BPSK) and quadrature phase shift keyed (QPSK) signals, at 20-Gb/s bitrate, in a 1-mm long amorphous silicon waveguide. A maximum FWM-efficiency of -26 dB was achieved by employing a pump power of just 70 mW, establishing this technology as a contender for the development of ultra-compact, low power, silicon photonics wavelength converter. Bit error ratio measurements demonstrated successful conversion with less than 1 dB penalty level, for both BPSK and QPSK signals (at BER = 10-5).},
keywords = {BSPK, nonlinear optics, QPSK, Silicon photonics, wavelength converter},
pubstate = {published},
tppubtype = {article}
}
In this letter, we demonstrate, for the first time, successful four wave mixing (FWM)-based wavelength conversion of binary phase shift keyed (BPSK) and quadrature phase shift keyed (QPSK) signals, at 20-Gb/s bitrate, in a 1-mm long amorphous silicon waveguide. A maximum FWM-efficiency of -26 dB was achieved by employing a pump power of just 70 mW, establishing this technology as a contender for the development of ultra-compact, low power, silicon photonics wavelength converter. Bit error ratio measurements demonstrated successful conversion with less than 1 dB penalty level, for both BPSK and QPSK signals (at BER = 10-5). |
2015
|
M J Strain, C Lacava, L Meriggi, I Cristiani, M Sorel Tunable Q-factor silicon microring resonators for ultra-low power parametric processes Journal Article Optics Letters, 40 (7), pp. 1274–1277, 2015. Abstract | Links | Tags: comb generation, integrated nonlinear photonics, nonlinear optics, Silicon photonics @article{Strain2015,
title = {Tunable Q-factor silicon microring resonators for ultra-low power parametric processes},
author = {M J Strain and C Lacava and L Meriggi and I Cristiani and M Sorel},
doi = {10.1364/OL.40.001274},
year = {2015},
date = {2015-01-01},
journal = {Optics Letters},
volume = {40},
number = {7},
pages = {1274--1277},
abstract = {A compact silicon ring resonator is demonstrated that allows simple electrical tuning of the ring coupling coefficient and Q-factor and therefore the resonant enhancement of on-chip nonlinear optical processes. Fabrication-induced variation in designed coupling fraction, crucial in the resonator performance, can be overcome using this postfabrication trimming technique. Tuning of the microring resonator across the critical coupling point is demonstrated, exhibiting a Q-factor tunable between 9000 and 96,000. Consequently, resonantly enhanced four-wave mixing shows tunable efficiency between -40 and -16.3 dB at an ultra-low on-chip pumppower of 0.7mW.},
keywords = {comb generation, integrated nonlinear photonics, nonlinear optics, Silicon photonics},
pubstate = {published},
tppubtype = {article}
}
A compact silicon ring resonator is demonstrated that allows simple electrical tuning of the ring coupling coefficient and Q-factor and therefore the resonant enhancement of on-chip nonlinear optical processes. Fabrication-induced variation in designed coupling fraction, crucial in the resonator performance, can be overcome using this postfabrication trimming technique. Tuning of the microring resonator across the critical coupling point is demonstrated, exhibiting a Q-factor tunable between 9000 and 96,000. Consequently, resonantly enhanced four-wave mixing shows tunable efficiency between -40 and -16.3 dB at an ultra-low on-chip pumppower of 0.7mW. |
