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2. Continuous Ultraviolet to Blue-Green Astrocomb

Author

Cheng, Yuk Shan, Dadi, Kamalesh, Mitchell, Toby, Thompson, Samantha, Piskunov, Nikolai, Wright, Lewis D., Gawith, Corin B. E., McCracken, Richard A., and Reid, Derryck T.

Subjects
Physics - Optics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The characterization of Earth-like exoplanets and precision tests of cosmological models using next-generation telescopes such as the ELT will demand precise calibration of astrophysical spectrographs in the visible region, where stellar absorption lines are most abundant. Astrocombs--lasers providing a broadband sequence of ultra-narrow, drift-free, regularly spaced optical frequencies on a multi-GHz grid--promise an atomically-traceable, versatile calibration scale, but their realization is challenging because of the need for ultra-broadband frequency conversion of mode-locked infrared lasers into the blue-green region. Here, we introduce a new concept achieving a broad, continuous spectrum by combining second-harmonic generation and sum-frequency-mixing in an aperiodically-poled MgO:PPLN waveguide to generate gap-free 390-520 nm light from a 1 GHz Ti:sapphire laser frequency comb. We lock a low-dispersion Fabry-Perot etalon to extract a sub-comb of bandwidth from 392-472 nm with a spacing of 30 GHz, visualizing the thousands of resulting comb modes on a high resolution cross-dispersion spectrograph. Complementary experimental data and simulations demonstrate the effectiveness of the approach for eliminating the spectral gaps present in second-harmonic-only conversion, in which weaker fundamental frequencies are suppressed by the quadratic \{chi}^((2)) nonlinearity. Requiring only ~100 pJ pulse energies, our concept establishes a practical new route to broadband UV-visible generation at GHz repetition rates., Comment: 14 pages; 4 figures

Published
2023
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3. Near-maximal two-photon entanglement for quantum communications at 2.1 $\mu$m

Author

Dada, Adetunmise C., Kaniewski, Jędrzej, Gawith, Corin, Lavery, Martin, Hadfield, Robert H., Faccio, Daniele, and Clerici, Matteo

Subjects
Quantum Physics, Physics - Applied Physics, Physics - Optics
Abstract

Owing to a reduced solar background and low propagation losses in the atmosphere, the 2- to 2.5-$\mu$m waveband is a promising candidate for daylight quantum communication. This spectral region also offers low losses and low dispersion in hollow-core fibers and in silicon waveguides. We demonstrate for the first time near-maximally entangled photon pairs at 2.1 $\mu$m that could support device independent quantum key distribution (DIQKD) assuming sufficiently high channel efficiencies. The state corresponds to a positive secure-key rate (0.254 bits/pair, with a quantum bit error rate of 3.8%) based on measurements in a laboratory setting with minimal channel loss and transmission distance. This is promising for the future implementation of DIQKD at 2.1 $\mu$m.

Published
2021
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4. Highly-Chirped Bragg Gratings for Integrated Silica Spectrometers

Author

Field, James W., Berry, Sam A., Bannerman, Rex H. S., Smith, Devin H., Gawith, Corin B. E., Smith, Peter G. R., and Gates, James C.

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

A blazed chirped Bragg grating in a planar silica waveguide device was used to create an integrated diffractive element for a spectrometer. The grating diffracts light from a waveguide and creates a wavelength dependent focus in a manner similar to a bulk diffraction grating spectrometer. An external imaging system is used to analyse the light, later device iterations plan to integrate detectors to make a fully integrated spectrometer. Devices were fabricated with grating period chirp rates in excess of 100nm/mm, achieving a focal length of 5.5mm. Correction of coma aberrations resulted in a device with a footprint of 20mm x 10mm, a peak FWHM resolution of 1.8nm, a typical FWHM resolution of 2.6nm and operating with a 160nm bandwidth centered at 1550nm., Comment: 13 Pages, 8 figures

Published
2020
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5. Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

Author

Berry, Sam A., Carpenter, Lewis G., Gray, Alan C., Smith, Peter G. R., and Gawith, Corin B. E.

Subjects
Physics - Optics
Abstract

We present a metallic zinc indiffused diced ridge waveguide in magnesium doped periodically poled lithium niobate (MgO:PPLN) capable of generating over 1 W of 780 nm with 70% efficiency. Our 40 mm long waveguide has near circular fundamental mode output with diameter 10.4 um and insertion loss of -1.17 dB. Using a commercial 2 W EDFA-based system, the SHG output power did not exhibit roll-off at maximum available pump power., Comment: 9 pages

Published
2019
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6. Two-photon Quantum Interference and Entanglement at 2 {\mu}m

Author

Prabhakar, Shashi, Shields, Taylor, Dada, Adetunmise, Ebrahim, Mehdi, Taylor, Gregor G., Morozov, Dmitry, Erotokritou, Kleanthis, Miki, Shigehito, Yabuno, Masahiro, Terai, Hirotaka, Gawith, Corin, Kues, Michael, Caspani, Lucia, Hadfield, Robert H., and Clerici, Matteo

Subjects
Quantum Physics, Physics - Optics
Abstract

Quantum-enhanced optical systems operating within the 2- to 2.5-$\mu$m spectral region have the potential to revolutionize emerging applications in communications, sensing, and metrology. However, to date, sources of entangled photons have been realized mainly in the near-infrared 700- to 1550-nm spectral window. Here, using custom-designed lithium niobate crystals for spontaneous parametric down-conversion and tailored superconducting nanowire single-photon detectors, we demonstrate two-photon interference and polarization-entangled photon pairs at 2090 nm. These results open the 2- to 2.5-$\mu$m mid-infrared window for the development of optical quantum technologies such as quantum key distribution in next-generation mid-infrared fiber communication systems and future Earth-to-satellite communications.

Published
2019
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7. 30 years of PPLN-what is old, what is new, and where next for PPLN and QPM material research?

Author

Smith Peter G.R., Tawy Goronwy, Bannerman Rex H., Gawith Corin B.E., Mennea Paolo, Davidson Noelia Palomar, and Gates James C

Subjects
Physics, QC1-999
Abstract

Since the first demonstration of electric field poling in 1993 - by workers at Sony - periodically poled materials (e.g. PPLN) have become ubiquitous in photonics. Their ability to allow quasi-phase matching opens up nonlinear optics across the full transparency bands of a material. In the case of PPLN this spans from the visible out to around 5 microns – offering a powerful route to create light in spectral regions where convenient lasers do not exist. This talk will cover underlying physics, materials, design, manufacturing and applications, as well as looking at next generation applications.

Published
2024
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8. Non-linear Frequency Conversion Waveguides for Quantum Technology

Author

Gates James C., Davidson Noelia Palomar, D’Souza Matthew P., Tawy Goronwy, Churchill Glenn, Mennea Paolo L., Iveson Peter, Smith Peter G.R., and Gawith Corin B.E.

Subjects
Physics, QC1-999
Abstract

This talk will describe the fabrication of periodically poled lithium niobate non-linear waveguides for the emerging quantum technology industry. It will address the challenges of optical engineering high-efficiency frequency conversion devices for the field and their application.

Published
2024
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9. A two-way photonic interface for linking Sr+ transition at 422 nm to the telecommunications C-band

Author

Wright, Thomas A., Francis-Jones, Robert J. A., Gawith, Corin B. E., Becker, Jonas N., Ledingham, Patrick M., Smith, Peter G. R., Nunn, Joshua, Mosley, Peter J., Brecht, Benjamin, and Walmsley, Ian A.

Subjects
Quantum Physics
Abstract

We report a single-stage bi-directional interface capable of linking Sr+ trapped ion qubits in a long-distance quantum network. Our interface converts photons between the Sr+ emission wavelength at 422 nm and the telecoms C-band to enable low-loss transmission over optical fiber. We have achieved both up- and down-conversion at the single photon level with efficiencies of 9.4% and 1.1% respectively. Furthermore we demonstrate noise levels that are low enough to allow for genuine quantum operation in the future., Comment: 5 pages, 4 figures

Published
2018
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16. Gravity sensing: cold atom trap onboard a 6U CubeSat

Author

Devani, Diviya, Maddox, Stephen, Renshaw, Ryan, Cox, Nigel, Sweeney, Helen, Cross, Trevor, Holynski, Michael, Nolli, Raffaele, Winch, Jonathan, Bongs, Kai, Holland, Karen, Colebrook, David, Adams, Neil, Quillien, Kevin, Buckle, James, Karde, Anupe, Farries, Mark, Legg, Tom, Webb, Richard, Gawith, Corin, Berry, Sam A., and Carpenter, Lewis

Published
2020
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19. Novel active waveguide devices in direct-bonded structures

Author

Gawith, Corin B. E. and Smith, Peter

Subjects
621, TK Electrical engineering. Electronics Nuclear engineering, QC Physics
Abstract

This thesis describes a series of experimental studies on the use of direct bonding for optical waveguide fabrication. The direct bonding technique involves contacting two ultra-clean polished surfaces to form an adhesive-free vacuum-tight bond. Optical materials bonded in this way can be formed into waveguide devices, and this work extends direct bonding to include periodically poled materials and a new solid-state ion-exchange process. The first result of this work describes the fabrication of a 5.5-mm-long, 12-µm-thick periodically poled LiNbO3 planar waveguide buried in LiTaO3. Frequency doubling experiments performed with this device demonstrate a conversion efficiency of 4.3 %W-1, a value 40% greater than that calculated for an optimised bulk device of similar length. Also demonstrated is a photorefractive iron-doped LiNbO3 waveguide buried in non-photorefractive magnesium-doped LiNbO3. In optical limiting experiments this device demonstrates a change in optical density of 2 and photorefractive response time of 5 milliseconds, representing 20 times greater optical limiting and 60 times faster operational speed than the bulk material. K+-Na+ ion-exchange between direct-bonded glass layers is studied and used as a novel solid-state technique for waveguide fabrication. This process is also developed to incorporate direct-UV-written channel waveguides in an ion-exchanged buried photosensitive glass layer. Finally, operation of a single-mode channel waveguide laser in neodymium-doped photosensitive SGBN glass (based on a composition of silica, germania, boron, and sodium) is demonstrated, with propagation losses of < 0.3 dB cm-1 and milliwatt-order lasing thresholds.

Published
2002

20. Developing Zinc-Indiffused Periodically Poled Lithium Niobate Ridge Waveguides for Quantum Applications at Visible Wavelengths

Author

Davidson, Noelia Palomar, primary, Tawy, Goronwy, additional, Churchill, Glenn M., additional, Mennea, Paolo L., additional, Bannerman, Rex H. S., additional, Smith, Peter G. R., additional, Wright, Lewis D., additional, Blanchard-Emmerson, Greg, additional, Gates, James C., additional, and Gawith, Corin B. E., additional

Published
2023
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27. Temperature-tunable UV generation using an Alexandrite laser and PPLN waveguides

Author

Tawy, Goronwy, Palomar Davidson, Noelia, Churchill, Glenn, Damzen, Michael J., Smith, Peter G.R., Gates, James C., and Gawith, Corin

Abstract

We present a simple and novel technique for achieving ultra-violet (UV) wavelength-tunable laser operation in the continuous-wave regime. Wavelength tunable operation in the near infrared is obtained from a compact two-mirror Alexandrite laser cavity by temperature tuning of the laser crystal. Second-harmonic-generation to the UV is then achieved at 376-379 nm and 384-386 nm by temperature tuning of a periodically-poled lithium-niobate (PPLN) waveguide. A maximum UV power of 1.3 mW from 185 mW infra-red pump throughput is obtained from a third-order PPLN Λ=6.1𝜇m grating. These results show promising potential for simple and wavelength tunable access to wavelengths at 360-400 nm.

Published
2023

29. Investigation into the writing dynamics of planar Bragg gratings using pulsed 213 nm radiation

Author

Ahmed, Q. Salman, primary, Field, James W., additional, Holmes, Christopher, additional, Oo, Swe Zin, additional, Mennea, Paolo L., additional, Bannerman, Rex H. S., additional, Cecil, Rod, additional, Churchill, Glenn, additional, Gawith, Corin B. E., additional, Smith, Peter G. R., additional, Gow, Paul C., additional, and Gates, James C., additional

Published
2023
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34. Investigation into multi-pass exposure of 213 nm pulsed UV writing for improved writing response

Author

Ahmed, Qazi, Field, James, Gow, Paul C., Holmes, Christopher, Bannerman, Rex, Mennea, Paolo, Gawith, Corin, Smith, Peter G R, and Gates, James

Abstract

We demonstrate an increase in achievable refractive index change of 1.2×10-3 in Ge-doped silica in writing waveguides and gratings using pulsed 213 nm light to deposit the same total fluence over multiple writing passes.

Published
2022

35. Holographically fabricated blazed chirped gratings for out-of-plane integrated beam focusing

Author

Ahmed, Qazi, Field, James, Gow, Paul C., Holmes, Christopher, Ko, Dong-Woo, Horak, Peter, Gawith, Corin, Smith, Peter G R, and Gates, James

Abstract

We demonstrate out-of-plane coupling of large (mm scale) and small (focusing) beams using holographically fabricated blazed-chirped gratings in doped silica at a 45° angle via a prism coupling mechanism.

Published
2022

36. Photosensitivity response of pulsed 213 nm light in planar Bragg grating writing

Author

Ahmed, Qazi, Field, James, Gow, Paul C., Oo, Swe zin Z, Holmes, Christopher, Bannerman, Rex, Mennea, Paolo, Gawith, Corin, Smith, Peter G R, and Gates, James

Abstract

We investigate the dynamics of pulsed 213 nm planar Bragg grating writing for a range of powers and fluences. We report the regime for achieving high index contrast, and where damage is likely to occur.

Published
2022

45. Near-maximal two-photon entanglement for optical quantum communication at 2.1 μm

Author

Dada, Adetunmise C., Kaniewski, Jędrzej, Gawith, Corin, Lavery, Martin, Hadfield, Robert H., Faccio, Daniele, and Clerici, Matteo

Abstract

Owing to a reduced solar background and low propagation losses in the atmosphere, the 2- to 2.5-μm waveband is a promising candidate for daylight quantum communication. This spectral region also offers low losses and low dispersion in hollow-core fibers and in silicon waveguides. We demonstrate for the first time near-maximally entangled photon pairs at 2.1 μm that could support device independent quantum key distribution (DIQKD) assuming sufficiently high channel efficiencies. The state corresponds to a positive secure-key rate (0.254 bits/pair, with a quantum bit error rate of 3.8%) based on measurements in a laboratory setting with minimal channel loss and transmission distance. This is promising for the future implementation of DIQKD at 2.1 μm.

Published
2021

46. Generation and characterization of two-photon entanglement in the mid infrared

Author

Dada, Adetunmise, primary, Shields, Taylor, additional, Prabhakar, Shashi, additional, Ebrahim, Mehdi, additional, Taylor, Gregor G., additional, Morozov, Dmitry V., additional, Erotokritou, Kleanthis, additional, Miki, Shigehito, additional, Yabuno, Masahiro, additional, Terai, Hirotaka, additional, Gawith, Corin B. E., additional, Kues, Michael, additional, Caspani, Lucia, additional, Hadfield, Robert H., additional, and Clerici, Matteo, additional

Published
2021
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47. Mid-infrared two-photon interference and polarization entanglement

Author

Shields, Taylor, primary, Dada, Adetunmise, additional, Prabhakar, Shashi, additional, Ebrahim, Mehdi, additional, Taylor, Gregor, additional, Morozov, Dmitry, additional, Erotokritou, Kleanthis, additional, Miki, Shigehito, additional, Yabuno, Masahiro, additional, Terai, Hirotaka, additional, Gawith, Corin, additional, Hadfield, Robert H., additional, Clerici, Matteo, additional, Caspani, Lucia, additional, and Kues, Michael, additional

Published
2021
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48. Four-port integrated waveguide coupler exploiting bi-directional propagation of two single-mode waveguides

Author

Weisen, Mathias, John, Gates, James, Gawith, Corin, Smith, Peter G.R., and Horak, Peter

Subjects
Physics::Optics
Abstract

We propose and numerically simulate a new and highly compact integrated 4x4 mode coupler based on two single-mode waveguides exploiting both forward and backward propagating directions to double the number of modes. The two parallel waveguides are coupled via long and short-period gratings to the co- and counter-propagating directions, respectively, of a single cladding mode of the device which acts as a bus between the waveguides. By connecting all end facets to optical circulators we construct a device with four input and output ports but only using two single-mode waveguides. Such a device can be fabricated in a single micromachined silica ridge structure. A photosensitive raised index layer is used for vertical confinement that supports multiple modes horizontally. We UV-write the waveguides and the Bragg gratings and provide a tilt angle to improve coupling. We have demonstrated this technology before for a polarizing waveguide-to-waveguide coupler and have simulated other unidirectional devices. We use coupled mode theory to simulate the system. By tailoring the grating parameters, we can achieve a wide variety of coupling ratios. Analytically, we find a set of solutions in which no light escapes via the cladding modes through the ends of the device and we have calculated device parameters to achieve a wide range of splitting ratios including coupling light from one input port equally into all output ports. Moreover, we derived analytically a set of parameters to implement a Walsh-Hadamard transformation and are investigating further options to implement a universal 4x4mode-coupler on this platform. We envisage that the device can be used for quantum information processing where two qubits are encoded in the waveguides using a photon in each propagation direction.

Published
2020

49. Photon-pair source at 2090 nm for long-distance quantum communication

Author

Prabhakar, Shashi, Shields, Taylor, Dada, Adetunmise, Ebrahim, Mehdi, Taylor, Gregor, Morozov, Dmitry, Eritokritou, Kleanthis, Miki, Shigehito, Yabuno, Mashahiro, Terai, Hirotaka, Gawith, Corin, Kues, Michael, Caspani, Lucia, Hadfield, Robert, and Clerici, Matteo

Subjects
Physics::Optics, Quantum Physics
Abstract

We report the generation of entangled photon pairs at 2090 nm, as a basis for free-space quantum communication in an atmospheric window with low solar background. The source is based on spontaneous parametric down-conversion in periodically poled lithium niobate crystal delivering high coincidence-to-accidental ratio. We demonstrate the two-photon Hong-Ou-Mandel quantum interference and polarization entanglement.

Published
2020

50. Two-photon quantum interference and entanglement at 2.1 µm

Author

Prabhakar, Shashi, Shields, Taylor, Dada, Adetunmise C., Ebrahim, Mehdi, Taylor, Gregor G., Morozov, Dmitry, Erotokritou, Kleanthis, Miki, Shigehito, Yabuno, Masahiro, Terai, Hirotaka, Gawith, Corin, Kues, Michael, Caspani, Lucia, Hadfield, Robert H., and Clerici, Matteo

Subjects
lithium niobate crystals, optical system, nanowire single-photon detectors, Physics::Optics, photons, ddc:500, Dewey Decimal Classification::500 | Naturwissenschaften
Abstract

Quantum-enhanced optical systems operating within the 2- to 2.5-μm spectral region have the potential to revolutionize emerging applications in communications, sensing, and metrology. However, to date, sources of entangled photons have been realized mainly in the near-infrared 700- to 1550-nm spectral window. Here, using custom-designed lithium niobate crystals for spontaneous parametric down-conversion and tailored superconducting nanowire single-photon detectors, we demonstrate two-photon interference and polarization-entangled photon pairs at 2090 nm. These results open the 2- to 2.5-μm mid-infrared window for the development of optical quantum technologies such as quantum key distribution in next-generation mid-infrared fiber communication systems and future Earth-to-satellite communications. Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).

Published
2020

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