We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error ... more We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error up to 3 dB for two parallel decision directed algorithms with feedback delay in an 11 Gbaud/s 16QAM coherent system.
The 15th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2002
(I) Department of Electronic Engineering, Dublin City University, D. 9, Ireland (liam.barry@dcuie... more (I) Department of Electronic Engineering, Dublin City University, D. 9, Ireland (liam.barry@dcuie) (2) Physics Department, Trinity College Dublin, Dublin 2, Ireland (3) Department of Electronic Engineering, University of Sheffield, Sheffield, SI 3JD, England
Investigation of the cross-channel interference in wavelength packet switched networks is present... more Investigation of the cross-channel interference in wavelength packet switched networks is presented. The results show that the output of a tunable laser needs to be correctly attenuated during the switching event in order to avoid system performance degradation.
Conference on Lasers and Electro-Optics 2010, 2010
ABSTRACT Two Michelson fiber interferometers were used to measure the in-band OSNR of a noisy sig... more ABSTRACT Two Michelson fiber interferometers were used to measure the in-band OSNR of a noisy signal between 5 and 30dB within ±0.5dB without prior knowledge of the noise-free extinction ratio of the signal.
ABSTRACT In-band OSNR from 5 to 30dB of a single 10G NRZ-OOK channel was measured by two fiber in... more ABSTRACT In-band OSNR from 5 to 30dB of a single 10G NRZ-OOK channel was measured by two fiber interferometers within an accuracy of ±0.5dB without requirement for knowledge of the noise-free extinction ratio of the signal.
ABSTRACT Monolithic semiconductor passively mode locked lasers (MLL) are very attractive componen... more ABSTRACT Monolithic semiconductor passively mode locked lasers (MLL) are very attractive components for many applications including high bit rate telecommunications, microwave photonics and instrumentation. Owing to the three dimensional confinement of the charge carriers, quantum dot based mode-locked lasers have been the subject of intense investigations because of their improved performance compared to conventional material systems. Indeed, the inhomogeneous gain broadening and the ultrafast absorption recovery dynamics are an asset for short pulse generation. Moreover, the weak coupling of amplified spontaneous emission with the guided modes plus low loss waveguide leads to low timing jitter. Our work concentrates on InAs quantum dash nanostructures grown on InP substrate, intended for applications in the 1.55 μm telecom window. InAs/InP quantum dash based lasers, in particular, have demonstrated efficient mode locking in single section Fabry-Perot configurations. The flat optical spectrum of about 12 nm, combined with the narrow RF beat note linewidth of about 10 kHz make them a promising technology for optical frequency comb generation. Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a single mode fiber.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Advanced optical pulse characterization methods are essential for high-speed optical communicatio... more Advanced optical pulse characterization methods are essential for high-speed optical communications. Recently non-iterative characterization of general optical pulses using sinusoidal optical phase modulation has been reported [12]. However, the usable phase ...
A novel two-section tunable laser diode is demonstrated by etching slots into the laser ridge. A ... more A novel two-section tunable laser diode is demonstrated by etching slots into the laser ridge. A discontinuous tuning-range of 30 nm was achieved with a SMSR of 38 dB. A wavelength switching time of 1.5 ns is demonstrated.
ABSTRACT Wavelength conversion via four-wave mixing (FWM) schemes of high-bit rate data formats a... more ABSTRACT Wavelength conversion via four-wave mixing (FWM) schemes of high-bit rate data formats are conventionally achieved using a strong pump source and a secondary nonlinear device, such as highly nonlinear fibre [1] or semiconductor optical amplifier [2]. In this work we obviate the need for a secondary nonlinear device, and achieve wavelength-conversion of high repetition-rate pulse trains by externally injecting a strong optical tone directly into the cavity of the 48GHz repetition-rate passively mode-locked semiconductor laser, achieving wavelength-conversion via partially-degenerate FWM. For the first time to our knowledge, we provide experimental results of the wavelength tunability of this wavelength-conversion scheme and show that the entire signal spectrum undergoes parametrically conversion.
Conference on Lasers and Electro-Optics 2012, 2012
ABSTRACT Device characterizations of QDash semiconductor lasers as a subchannel comb generator ar... more ABSTRACT Device characterizations of QDash semiconductor lasers as a subchannel comb generator are presented, including measurements of electric field, optical linewidth, and mode coherence out to 1.5THz spectral mode separation.
European Conference and Exhibition on Optical Communication, 2012
ABSTRACT Phase locked frequency combs spanning > 1.5 THz have been generated using passive... more ABSTRACT Phase locked frequency combs spanning > 1.5 THz have been generated using passively mode locked quantum dash based lasers emitting at 1.55 µm. These combs are particularly suited for future OFDM transmission systems.
China-Ireland International Conference on Information and Communications Technologies (CIICT 2008), 2008
ABSTRACT This paper investigates the use of a two-photon absorption photodetector for all-optical... more ABSTRACT This paper investigates the use of a two-photon absorption photodetector for all-optical signal processing. Continuous, wavelength selective chromatic dispersion monitoring in a high-speed multi-wavelength system is discussed. The reduction of multiple access interference in an optical code division multiple access network using a TPA photodetector is also presented.
We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error ... more We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error up to 3 dB for two parallel decision directed algorithms with feedback delay in an 11 Gbaud/s 16QAM coherent system.
The 15th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2002
(I) Department of Electronic Engineering, Dublin City University, D. 9, Ireland (liam.barry@dcuie... more (I) Department of Electronic Engineering, Dublin City University, D. 9, Ireland (liam.barry@dcuie) (2) Physics Department, Trinity College Dublin, Dublin 2, Ireland (3) Department of Electronic Engineering, University of Sheffield, Sheffield, SI 3JD, England
Investigation of the cross-channel interference in wavelength packet switched networks is present... more Investigation of the cross-channel interference in wavelength packet switched networks is presented. The results show that the output of a tunable laser needs to be correctly attenuated during the switching event in order to avoid system performance degradation.
Conference on Lasers and Electro-Optics 2010, 2010
ABSTRACT Two Michelson fiber interferometers were used to measure the in-band OSNR of a noisy sig... more ABSTRACT Two Michelson fiber interferometers were used to measure the in-band OSNR of a noisy signal between 5 and 30dB within ±0.5dB without prior knowledge of the noise-free extinction ratio of the signal.
ABSTRACT In-band OSNR from 5 to 30dB of a single 10G NRZ-OOK channel was measured by two fiber in... more ABSTRACT In-band OSNR from 5 to 30dB of a single 10G NRZ-OOK channel was measured by two fiber interferometers within an accuracy of ±0.5dB without requirement for knowledge of the noise-free extinction ratio of the signal.
ABSTRACT Monolithic semiconductor passively mode locked lasers (MLL) are very attractive componen... more ABSTRACT Monolithic semiconductor passively mode locked lasers (MLL) are very attractive components for many applications including high bit rate telecommunications, microwave photonics and instrumentation. Owing to the three dimensional confinement of the charge carriers, quantum dot based mode-locked lasers have been the subject of intense investigations because of their improved performance compared to conventional material systems. Indeed, the inhomogeneous gain broadening and the ultrafast absorption recovery dynamics are an asset for short pulse generation. Moreover, the weak coupling of amplified spontaneous emission with the guided modes plus low loss waveguide leads to low timing jitter. Our work concentrates on InAs quantum dash nanostructures grown on InP substrate, intended for applications in the 1.55 μm telecom window. InAs/InP quantum dash based lasers, in particular, have demonstrated efficient mode locking in single section Fabry-Perot configurations. The flat optical spectrum of about 12 nm, combined with the narrow RF beat note linewidth of about 10 kHz make them a promising technology for optical frequency comb generation. Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a single mode fiber.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Advanced optical pulse characterization methods are essential for high-speed optical communicatio... more Advanced optical pulse characterization methods are essential for high-speed optical communications. Recently non-iterative characterization of general optical pulses using sinusoidal optical phase modulation has been reported [12]. However, the usable phase ...
A novel two-section tunable laser diode is demonstrated by etching slots into the laser ridge. A ... more A novel two-section tunable laser diode is demonstrated by etching slots into the laser ridge. A discontinuous tuning-range of 30 nm was achieved with a SMSR of 38 dB. A wavelength switching time of 1.5 ns is demonstrated.
ABSTRACT Wavelength conversion via four-wave mixing (FWM) schemes of high-bit rate data formats a... more ABSTRACT Wavelength conversion via four-wave mixing (FWM) schemes of high-bit rate data formats are conventionally achieved using a strong pump source and a secondary nonlinear device, such as highly nonlinear fibre [1] or semiconductor optical amplifier [2]. In this work we obviate the need for a secondary nonlinear device, and achieve wavelength-conversion of high repetition-rate pulse trains by externally injecting a strong optical tone directly into the cavity of the 48GHz repetition-rate passively mode-locked semiconductor laser, achieving wavelength-conversion via partially-degenerate FWM. For the first time to our knowledge, we provide experimental results of the wavelength tunability of this wavelength-conversion scheme and show that the entire signal spectrum undergoes parametrically conversion.
Conference on Lasers and Electro-Optics 2012, 2012
ABSTRACT Device characterizations of QDash semiconductor lasers as a subchannel comb generator ar... more ABSTRACT Device characterizations of QDash semiconductor lasers as a subchannel comb generator are presented, including measurements of electric field, optical linewidth, and mode coherence out to 1.5THz spectral mode separation.
European Conference and Exhibition on Optical Communication, 2012
ABSTRACT Phase locked frequency combs spanning > 1.5 THz have been generated using passive... more ABSTRACT Phase locked frequency combs spanning > 1.5 THz have been generated using passively mode locked quantum dash based lasers emitting at 1.55 µm. These combs are particularly suited for future OFDM transmission systems.
China-Ireland International Conference on Information and Communications Technologies (CIICT 2008), 2008
ABSTRACT This paper investigates the use of a two-photon absorption photodetector for all-optical... more ABSTRACT This paper investigates the use of a two-photon absorption photodetector for all-optical signal processing. Continuous, wavelength selective chromatic dispersion monitoring in a high-speed multi-wavelength system is discussed. The reduction of multiple access interference in an optical code division multiple access network using a TPA photodetector is also presented.
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Papers by Liam P Barry