ORCID Profile
0000-0002-9989-5275
Current Organisation
Technical University of Denmark
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Publisher: Optica Publishing Group
Date: 06-04-2021
DOI: 10.1364/OME.424872
Abstract: This is an introduction to the feature issue of Optical Materials Express on Optical Fibers: Materials and Applications .
Publisher: The Optical Society
Date: 24-07-2017
DOI: 10.1364/OL.42.002943
Publisher: Springer Science and Business Media LLC
Date: 12-06-2019
DOI: 10.1038/S41598-019-44951-4
Abstract: M-type fibers have the exceptional property that the higher-order LP 0n modes are core-confined and easily excited, while the LP 01 and other modes are confined to a high-index ring surrounding the core, so they are not easily excited. This has profound consequences for mid-infrared supercontinuum sources, where the high zero-dispersion wavelength of chalcogenide and ZBLAN fibers means that exotic pump sources have so far been necessary. We show here that in chalcogenide and ZBLAN M-type fibers the lower ZDW of the core-confined higher-order LP 02 mode can be in the range of 2 to 3 µm (around 1.55 µm), while the fiber still has a large core diameter and thus supports high average power. This will allow established pump laser technology to be used in future high-power mid-infrared supercontinuum sources.
Publisher: Springer Science and Business Media LLC
Date: 24-08-2021
DOI: 10.1038/S41598-020-61847-W
Abstract: Deep-UV (DUV) supercontinuum (SC) sources based on gas-filled hollow-core fibers constitute perhaps the most viable solution towards ultrafast, compact, and tunable lasers in the UV spectral region, which can even also extend into the mid-infrared (IR). Noise and spectral stability of such broadband sources are key parameters that define their true potential and suitability towards real-world applications. In order to investigate the spectral stability and noise levels in these fiber-based DUV sources, we generate an SC spectrum that extends from 180 nm (through phase-matched dispersive waves - DWs) to 4 μm by pumping an argon-filled hollow-core anti-resonant fiber at a mid-IR wavelength of 2.45 μm. We characterize the long-term stability of the source over several days and the pulse-to-pulse relative intensity noise (RIN) of the DW at 275 nm. The results indicate no sign of spectral degradation over 110 hours, but the RIN of the DW pulses at 275 nm is found to be as high as 33.3%. Numerical simulations were carried out to investigate the spectral distribution of the RIN and the results confirm the experimental measurements and that the poor noise performance is due to the high RIN of the mid-IR pump laser, which was hitherto not considered in numerical modelling of these sources. The results presented herein provide an important step towards an understanding of the noise mechanism underlying such complex light-gas nonlinear interactions and demonstrate the need for pump laser stabilization.
Publisher: The Optical Society
Date: 14-01-2016
DOI: 10.1364/OE.24.001253
Publisher: Springer Science and Business Media LLC
Date: 14-03-2019
DOI: 10.1038/S41598-019-39302-2
Abstract: Supercontinuum (SC) generation based on ultrashort pulse compression constitutes one of the most promising technologies towards ultra-wide bandwidth, high-brightness, and spatially coherent light sources for applications such as spectroscopy and microscopy. Here, multi-octave SC generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the mid-infrared (mid-IR) having an output energy of 5 μJ. This was obtained by pumping at the center wavelength of the first anti-resonant transmission window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~8 μJ. The mechanism behind the extreme spectral broadening relies upon intense soliton-plasma nonlinear dynamics which leads to efficient soliton self-compression and phase-matched dispersive wave (DW) emission in the DUV region. The strongest DW is observed at 275 nm which corresponds to the calculated phase-matching wavelength of the pump. Furthermore, the effect of changing the pump pulse energy and gas pressure on the nonlinear dynamics and their direct impact on SC generation was investigated. This work represents another step towards gas-filled fiber-based coherent sources, which is set to have a major impact on applications spanning from DUV to mid-IR.
Publisher: IEEE
Date: 06-2017
Publisher: The Optical Society
Date: 23-12-2016
DOI: 10.1364/OME.7.000286
Publisher: Shanghai Institute of Optics and Fine Mechanics
Date: 2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2015
Publisher: Optica Publishing Group
Date: 2020
DOI: 10.1364/MICS.2020.MTH1C.6
Abstract: A mid-IR 4.22 µm Raman laser targeting CO 2 absorption line is reported based on a hydrogen-filled hollow-core fiber. Quantum efficiency as high as 74% was achieved at 20 bar with 17.6 µJ pulse energy.
Publisher: The Optical Society
Date: 16-05-2019
DOI: 10.1364/OME.9.002617
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2011
Publisher: The Optical Society
Date: 06-2017
DOI: 10.1364/OL.42.002232
Publisher: Optica Publishing Group
Date: 23-03-2020
DOI: 10.1364/OL.389613
Abstract: In this Letter, we demonstrate a high pulse energy and linearly polarized mid-infrared Raman fiber laser targeting the strongest absorption line of C O 2 at ∼ 4.2 µ m . This laser was generated from a hydrogen ( H 2 )-filled antiresonant hollow-core fiber, pumped by a custom-made 1532.8 nm Er-doped fiber laser delivering 6.9 ns pulses and 11.6 kW peak power. A quantum efficiency as high as 74% was achieved, to yield 17.6 µJ pulse energy at 4.22 µm. Less than 20 bar H 2 pressure was required to maximize the pulse energy since the transient Raman regime was efficiently suppressed by the long pump pulses.
Publisher: IEEE
Date: 06-2017
Publisher: Elsevier BV
Date: 06-2020
Publisher: The Optical Society
Date: 20-12-2018
Publisher: The Optical Society
Date: 19-02-2013
DOI: 10.1364/OE.21.004758
Publisher: SPIE
Date: 07-03-2019
DOI: 10.1117/12.2509575
Publisher: The Optical Society
Date: 27-01-2016
DOI: 10.1364/OME.6.000649
Publisher: The Optical Society
Date: 03-05-2018
Publisher: OSA
Date: 2019
Publisher: The Optical Society
Date: 07-04-2011
DOI: 10.1364/OE.19.007790
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2510284
Publisher: Optica Publishing Group
Date: 2020
Abstract: We present the generation of mid-IR light in anti-resonant hollow-core fiber using Raman-active gas for 4.2µm laser and Raman-inactive gas for multi-octave SC spanning from 200 nm to 4µm.
Publisher: Optica Publishing Group
Date: 2021
DOI: 10.1364/CLEO_SI.2021.SW3R.6
Abstract: A Raman laser with distinct lines at 1683, 1868, 2099, and 2394 nm is reported based on a hydrogen-filled nested anti-resonant fiber, with high pulse energies of 18.25, 14.4, 14.1, and 8.2 µJ, respectively.
Publisher: MDPI AG
Date: 22-07-2021
Abstract: Near- and mid-infrared optical coherence tomography (OCT) is evaluated as a non-destructive and non-contact reflection imaging modality for inspection of industrial and marine coatings. Near-infrared OCT was used to obtain high-resolution images (~6/2 µm lateral/axial) of hidden subsurface cracks and defects in a resin base coating, which had been exposed to high pressure and high temperature to study coating degradation in hostile environments. Mid-infrared OCT was employed for high-resolution (~15/8.5 µm lateral/axial) subsurface inspection of highly scattering marine coatings, demonstrating monitoring of wet film thickness and particle dispersion during curing of a 210 µm layer of antifouling coating, and detection of substrate corrosion through 369 µm of high-gloss alkyd enamel. Combining high-resolution and fast, non-invasive scanning, OCT is therefore considered a promising tool for studying coating performance and for industrial inspection.
Publisher: IOP Publishing
Date: 21-08-2015
Publisher: Victoria University of Wellington Library
Date: 07-2005
DOI: 10.26686/NZAROE.V0I15.1507
Abstract: At a time of economic growth in Ireland, the declining numbers of students enrolling in the sciences is emerging as an educational concern. Using a 2002 Government of Ireland commissioned report on science: The Task Force on the Physical Sciences (TFPS) as a guide, this article examines initiatives aimed at promoting science education in relation to recent social, philosophical, economic and cultural changes in the Republic of Ireland. Shifts in thinking about science teaching and innovative pedagogical strategies at both the secondary and tertiary levels of education are discussed.
Publisher: The Optical Society
Date: 13-01-2021
DOI: 10.1364/OME.414973
Publisher: SPIE
Date: 28-09-2015
DOI: 10.1117/12.2194822
Publisher: SPIE
Date: 02-05-2014
DOI: 10.1117/12.2054304
Publisher: American Physical Society (APS)
Date: 27-11-2017
Publisher: OSA
Date: 2018
Publisher: MDPI AG
Date: 15-10-2020
Abstract: We present a fully integrated optical ammonia sensor, based on a photonic integrated circuit (PIC) with a tunable laser source and a hollow-core fiber (HCF) as gas interaction cell. The PIC also contains a photodetector that can be used to record the absorption signal with the same device. The sensor targets an ammonia absorption line at 1522.45 nm, which can be reached with indium phosphide-based telecom compatible PICs. A 1.65-m long HCF is connected on both ends to a single-mode fiber (SMF) with a mechanical splice that allows filling and purging of the fiber within a few minutes. We show the detection of a 5% ammonia gas concentration, as a proof of principle of our sensor and we show the potential to even detect much lower concentrations. This work paves the way towards a low-cost, integrated and portable gas sensor with potential applications in environmental gas sensing.
Publisher: The Optical Society
Date: 20-03-2018
DOI: 10.1364/BOE.9.001762
Publisher: SPIE
Date: 17-10-2012
DOI: 10.1117/12.977859
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2021
Publisher: SPIE
Date: 18-04-2021
DOI: 10.1117/12.2592409
Publisher: OSA
Date: 2018
Publisher: SPIE
Date: 07-03-2019
DOI: 10.1117/12.2510351
Publisher: The Optical Society
Date: 04-09-2018
DOI: 10.1364/OE.26.024357
Publisher: OSA
Date: 2016
Publisher: SPIE
Date: 23-04-2017
DOI: 10.1117/12.2265884
Publisher: Optica Publishing Group
Date: 19-01-2021
DOI: 10.1364/OL.411003
Abstract: In this work, we present a high-pulse-energy multi-wavelength Raman laser spanning from 1.53 µm up to 2.4 µm by employing the cascaded rotational stimulated Raman scattering effect in a 5 m hydrogen ( H 2 )-filled nested anti-resonant fiber, pumped by a linearly polarized Er/Yb fiber laser with a peak power of ∼ 13 k W and pulse duration of ∼ 7 n s in the C-band. The developed Raman laser has distinct lines at 1683 nm, 1868 nm, 2100 nm, and 2400 nm, with pulse energies as high as 18.25 µJ, 14.4 µJ, 14.1 µJ, and 8.2 µJ, respectively. We demonstrate how the energy in the Raman lines can be controlled by tuning the H 2 pressure from 1 bar to 20 bar.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2021
Publisher: The Optical Society
Date: 27-02-2014
DOI: 10.1364/OE.22.005270
Publisher: OSA
Date: 2018
Publisher: IEEE
Date: 06-2017
Publisher: The Optical Society
Date: 13-03-2017
DOI: 10.1364/OL.42.001161
Publisher: Optica Publishing Group
Date: 2020
DOI: 10.1364/CLEO_AT.2020.JTH2E.8
Abstract: Deep-UV radiation is achieved through dispersive wave generation in an argon-filled anti-resonant fiber utilizing a nonlinearly compressed 1030nm pump. Relative intensity noise is characterized at 280nm, with 1.6% achieved for optimal argon-pressure and pump parameters.
Publisher: The Optical Society
Date: 06-04-2021
Publisher: SPIE
Date: 18-04-2021
DOI: 10.1117/12.2592717
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2020
Publisher: The Optical Society
Date: 14-01-2016
DOI: 10.1364/OE.24.001206
Publisher: The Optical Society
Date: 22-06-2017
DOI: 10.1364/OE.25.015336
Publisher: Springer Science and Business Media LLC
Date: 22-06-2022
DOI: 10.1038/S41598-022-14869-5
Abstract: In this study, for the first time, a Photoacoustic Microscopy instrument driven by a single optical source operating over a wide spectral range (475–2400 nm), covering slightly more than two octaves is demonstrated. Xenopus laevis tadpoles were imaged in vivo using the whole spectral range of 2000 nm of a supercontinuum optical source, and a novel technique of mapping absorbers is also demonstrated, based on the supposition that only one chromophore contributes to the photoacoustic signal of each in idual voxel in the 3D photoacoustic image. By using a narrow spectral window (of 25 nm bandwidth) within the broad spectrum of the supercontinuum source at a time, in vivo hyper-spectral Photoacoustic images of tadpoles are obtained. By post-processing pairs of images obtained using different spectral windows, maps of five endogenous contrast agents (hemoglobin, melanin, collagen, glucose and lipids) are produced.
Publisher: SPIE
Date: 27-04-2016
DOI: 10.1117/12.2227843
Publisher: OSA
Date: 2018
Publisher: OSA
Date: 2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2017
Publisher: Springer Science and Business Media LLC
Date: 28-10-2020
DOI: 10.1038/S41598-020-75072-Y
Abstract: The realization of a table-top tunable deep-ultraviolet (UV) laser source with excellent noise properties would significantly benefit the scientific community, particularly within imaging and spectroscopic applications, where source noise has a crucial role. Here we provide a thorough characterization of the pulse-to-pulse relative intensity noise (RIN) of such a deep-UV source based on an argon (Ar)-filled anti-resonant hollow-core (AR HC) fiber. Suitable pump pulses are produced using a compact commercially available laser centered at 1030 nm with a pulse duration of 400 fs, followed by a nonlinear compression stage that generates pulses with 30 fs duration, 24.2 μJ energy at 100 kHz repetition rate and a RIN of 1%. Pump pulses coupled into the AR HC fiber undergo extreme spectral broadening creating a supercontinuum, leading to efficient energy transfer to a phase-matched resonant dispersive wave (RDW) in the deep-UV spectral region. The center wavelength of the RDW could be tuned between 236 and 377 nm by adjusting the Ar pressure in a 140 mm length of fiber. Under optimal pump conditions the RIN properties were demonstrated to be exceptionally good, with a value as low as 1.9% at ~ 282 nm. The RIN is resolved spectrally for the pump pulses, the generated RDW and the broadband supercontinuum. These results constitute the first broadband RIN characterization of such a deep-UV source and provide a significant step forward towards a stable, compact and tunable laser source for applications in the deep-UV spectral region.
Publisher: The Optical Society
Date: 13-01-2021
DOI: 10.1364/OME.412299
Publisher: OSA
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 14-08-2014
DOI: 10.1038/SREP06057
Abstract: The combination of chalcogenide glasses with polymer photonic crystal fibers (PCFs) is a difficult and challenging task due to their different thermo-mechanical material properties. Here we report the first experimental realization of a hybrid polymer-chalcogenide PCF with integrated As 2 S 3 glass nanofilms at the inner surface of the air-channels of a poly-methyl-methacrylate (PMMA) PCF. The integrated high refractive index glass films introduce distinct antiresonant transmission bands in the 480–900 nm wavelength region. We demonstrate that the ultra-high Kerr nonlinearity of the chalcogenide glass makes the polymer PCF nonlinear and provides a possibility to shift the transmission band edges as much as 17 nm by changing the intensity. The proposed fabrication technique constitutes a new highway towards all-fiber nonlinear tunable devices based on polymer PCFs, which at the moment is not possible with any other fabrication method.
Publisher: IEEE
Date: 06-2017
Publisher: SPIE
Date: 28-09-2015
DOI: 10.1117/12.2194963
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-09-2020
Publisher: AIP Publishing
Date: 06-2021
DOI: 10.1063/5.0050446
Abstract: Unlocking the true potential of optical spectroscopy on the nanoscale requires development of stable and low-noise laser sources. Here, we have developed a low-noise supercontinuum (SC) source based on an all-normal dispersion fiber pumped by a femtosecond fiber laser and demonstrate high resolution, spectrally resolved near-field measurements in the near-infrared (NIR) region. Specifically, we explore the reduced-noise requirements for aperture-less scattering-type scanning near-field optical microscopy (s-SNOM), including inherent pulse-to-pulse fluctuation of the SC. We use our SC light source to demonstrate the first NIR, spectrally resolved s-SNOM measurement, a situation where state-of-the-art commercial SC sources are too noisy to be useful. We map the propagation of surface plasmon polariton (SPP) waves on monocrystalline gold platelets in the wavelength region of 1.34–1.75 μm in a single measurement, thereby characterizing experimentally the dispersion curve of the SPP in the NIR. Our results represent a technological breakthrough that has the potential to enable a wide range of new applications of low-noise SC sources in near-field studies.
Publisher: Optica Publishing Group
Date: 14-05-2021
DOI: 10.1364/OL.423823
Abstract: A hybrid optical fiber comprising metal electrodes, high performance polymers, and a highly nonlinear glass core is presented in this work as a novel, to the best of our knowledge, platform for mid-infrared nonlinear devices. The fiber allows for electrical tuning of the temperature by joule heating using a set of embedded tungsten wires. Unlike temperature tuning by an external heater, this results in a strong modulation, which introduces alternating signs of its dispersion. Enhanced spectral broadening through supercontinuum generation in the mid-infrared due to this modulation is investigated numerically.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Christos Markos.