Photonic lanterns are low-loss mode convertors easily integrated with optical fiber technologies.... more Photonic lanterns are low-loss mode convertors easily integrated with optical fiber technologies. We present the proof of concept of a focal plane low-order wavefront sensor based on a 19-core multicore photonic lantern and deep learning.
14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020), 2020
We discuss the use of spatial mode sorters as coronagraphs capable of operating near the fundamen... more We discuss the use of spatial mode sorters as coronagraphs capable of operating near the fundamental limits at small inner working angles.
2013 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching, 2013
Photonic lanterns allow for transforming a multimode waveguide into a discrete number of single-m... more Photonic lanterns allow for transforming a multimode waveguide into a discrete number of single-mode ones. We will present the operating principle of these unique devices and their current and future applications in Astronomy and Telecommunications.
Optical and Infrared Interferometry and Imaging VII, 2020
With thousands of confirmed exoplanets, the era of discovery is giving way to that of characteriz... more With thousands of confirmed exoplanets, the era of discovery is giving way to that of characterization. Direct imaging is crucial, but extremely difficult due to high star-to-planet contrasts and high angular resolutions. Nulling interferometry, which suppresses contaminating starlight via destructive interference, aims to meet this challenge. A pathfinder of this technique is the GLINT nuller: a 6-baseline, spectrally dispersed pupil-remapping interferometer deployed at the Subaru telescope, in which a single photonic chip performs all the critical optical processes. We present the instrument, novel data processing based on self-calibrating methods, laboratory characterization and the latest on-sky results.
Hector1, 5 is the next dark-time instrument to be commissioned on the Anglo-Australian Telescope ... more Hector1, 5 is the next dark-time instrument to be commissioned on the Anglo-Australian Telescope (AAT) and will include 21 IFUs called hexabundles2-4, 6 that will sit on the 2-degree top end. These hexabundles are bundles of fibres that are packed in a regular hexagonal array. They are built in sizes of 37, 61, 91, 127, and 169 fibres. The distribution of sizes of hexabundles was calculated to maximize the efficiency of the galaxy survey. The Hector hexabundles have been optimized for this instrument. Their regular hexagonal packing has been developed to improve data reduction accuracy, and the fibres have had a short length of their cladding etched in order to pack them as tightly as possible without reducing the optical quality of the devices.
Orbital angular momentum (OAM) beams, have attracted great attention in recent years. An OAM beam... more Orbital angular momentum (OAM) beams, have attracted great attention in recent years. An OAM beam with a phase singularity is characterized by a helical phase front which provides an additional degree of freedom for wide amount of classical and quantum optical applications. However, despite many attempts to generate and manipulate OAM beams, a robust, reliable and scalable technique to directly address generation, multiplexing and low-loss transmission of the distinct OAM beams is still in great demand. Here, we review the development of all-fiber, ring core photonics lantern mode multiplexer to generate high quality OAM beams up to the second order within a broad spectral range of >550 nm. Our device is a 5-mode mode selective photonic lantern (MSPL) with an annular refractive index profile which is fully compatible with well-established ring core and vortex transmission fibers. Through the excitation of pairs of degenerate linearly polarized (LP) modes of the MSPL, we demonstra...
We experimentally demonstrate a transverse mode-selective fiber laser using a photonic lantern. T... more We experimentally demonstrate a transverse mode-selective fiber laser using a photonic lantern. The output modes of laser are switchable among the 6 LP modes supported by the gain fiber. Their slope efficiency, optical spectra, and mode profiles are measured. Introduction Large mode-area optical fiber can support highorder of linear polarization (LP) modes. There are many motivations for producing high-order transverse modes of laser radiation. For example, it has been shown that high-order LP modes have higher threshold for detrimental nonlinear loss processes, such as stimulated Brillouin scattering (SBS), in comparison with the fundamental mode. It has also been shown that high-order modes can reduce the sensitivity to mode profile distortion and improve energy extraction in pulse laser systems. In fiber sensor systems, high-order LP modes in few mode fiber (FMF) allow for increasing the measurement sensitivity of fiber bending. Recent research also indicate that specific laser b...
Increasing concern for the ongoing availability and efficacy of herbicides is driving interest in... more Increasing concern for the ongoing availability and efficacy of herbicides is driving interest in the development of alternative physical and thermal weed control methods. Fortunately, improvements in weed detection through advancements in computing hardware and deep learning algorithms are creating an opportunity to use novel weed control tools, such as lasers, in large-scale cropping systems. For alternative control options, there are two key weed control timing opportunities, early and late post-crop emergence. Weed density for the early timing is typically higher, with a shorter window for control. Conversely, late post-emergent treatment of surviving and late-emerging weeds would occur in lower densities of larger and more variably sized weeds, given a prior weed control effort, but with a longer available weed control period. Research in laser weeding to date has primarily focused on early growth stage weeds and the ability of this approach to control larger weeds remains unkn...
Asia Communications and Photonics Conference 2015, 2015
3D printing of optical fibre preforms is reported. Tens of meters of air-structured optical fibre... more 3D printing of optical fibre preforms is reported. Tens of meters of air-structured optical fibre made from a propriety combination of acrylonitrile butadiene styrene (ABS) and polystyrene is drawn. Propagation losses better than α < 1.5 dB/cm @ 632 nm, α < 0.75 dB/cm @ 1064 nm, and α < 1.51 dB/cm @ 1550 nm are obtained. This work signals a milestone in the history of optical fibre manufacturing, further revolutionised by future 3D printing of materials such as silica and other glasses as well as sapphire and the like.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT Mode convertors couple light from one fibre mode to another. They have applications in d... more ABSTRACT Mode convertors couple light from one fibre mode to another. They have applications in dispersion compensation, nonlinear optics and atom guiding for example. We demonstrate coupling from the fundamental LP01 mode to the circularly symmetric TE01 mode, which has applications for atom guidance.
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
Transitions in core shape are formed in photonic crystal fibres by differential pressurisation of... more Transitions in core shape are formed in photonic crystal fibres by differential pressurisation of the holes and localised heating. Low-loss anamorphic transitions to rectangular and annular cores are formed, and improved coupling from diode lasers to fibres thereby demonstrated.
(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005
Tapering of conventional and photonic crystal fibres can be used to make glass-air waveguides dow... more Tapering of conventional and photonic crystal fibres can be used to make glass-air waveguides down to submicron scales, and gives them ready-made low-loss interfaces to simplify input and output coupling.
ABSTRACT New methods have been developed in post-processing and tapering of PCFs to achieve a var... more ABSTRACT New methods have been developed in post-processing and tapering of PCFs to achieve a variety of low-loss optical devices. Interfacing between waveguides with very different properties and highly efficient mode convertors are presented.
2007 9th International Conference on Transparent Optical Networks, 2007
ABSTRACT We have used tapering of photonic crystal fibres to make all-fibre mode converters for t... more ABSTRACT We have used tapering of photonic crystal fibres to make all-fibre mode converters for the LP11 and LP02 modes. The devices rely on adiabatic propagation rather than resonant coupling, allowing high extinction across a wide wavelength range.
ABSTRACT A miniature curvature wavefront sensor with a coherent fiber image bundle is proposed in... more ABSTRACT A miniature curvature wavefront sensor with a coherent fiber image bundle is proposed in which a miniature lateral displacement beamsplitter is designed to obtain the intra- and extra- focus images from a telescope simultaneously at its exit. The two images are received and relayed by two coherent fiber image bundles. The relayed images are then re-imaged to one camera and processed to obtain the input wavefront at telescope pupil. The whole device is quite compact and can be driven by a “Starbug” fiber positioning device currently under development within the Australian Astronomical Observatory. In this paper, the performance of the proposed sensor is investigated in details by applying a simulated atmospheric turbulence at the telescope pupil plane. We study the offset distance of two image measurement planes, fiber core size, fiber fill factor and the magnitude of natural guide star effects to its performance. This study provides guidance to the sensor design.
We describe two all-fiber devices for converting light from the fundamental mode to the second-or... more We describe two all-fiber devices for converting light from the fundamental mode to the second-order set of modes in optical fibers. The first is made by controlled hole collapse in a photonic crystal fiber, and the second is a twisted fused coupler made from few-moded conventional fiber. As well as having applications within fiber optics, the devices can be used to generate azimuthally polarized free-space beams.
Photonic lanterns are low-loss mode convertors easily integrated with optical fiber technologies.... more Photonic lanterns are low-loss mode convertors easily integrated with optical fiber technologies. We present the proof of concept of a focal plane low-order wavefront sensor based on a 19-core multicore photonic lantern and deep learning.
14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020), 2020
We discuss the use of spatial mode sorters as coronagraphs capable of operating near the fundamen... more We discuss the use of spatial mode sorters as coronagraphs capable of operating near the fundamental limits at small inner working angles.
2013 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching, 2013
Photonic lanterns allow for transforming a multimode waveguide into a discrete number of single-m... more Photonic lanterns allow for transforming a multimode waveguide into a discrete number of single-mode ones. We will present the operating principle of these unique devices and their current and future applications in Astronomy and Telecommunications.
Optical and Infrared Interferometry and Imaging VII, 2020
With thousands of confirmed exoplanets, the era of discovery is giving way to that of characteriz... more With thousands of confirmed exoplanets, the era of discovery is giving way to that of characterization. Direct imaging is crucial, but extremely difficult due to high star-to-planet contrasts and high angular resolutions. Nulling interferometry, which suppresses contaminating starlight via destructive interference, aims to meet this challenge. A pathfinder of this technique is the GLINT nuller: a 6-baseline, spectrally dispersed pupil-remapping interferometer deployed at the Subaru telescope, in which a single photonic chip performs all the critical optical processes. We present the instrument, novel data processing based on self-calibrating methods, laboratory characterization and the latest on-sky results.
Hector1, 5 is the next dark-time instrument to be commissioned on the Anglo-Australian Telescope ... more Hector1, 5 is the next dark-time instrument to be commissioned on the Anglo-Australian Telescope (AAT) and will include 21 IFUs called hexabundles2-4, 6 that will sit on the 2-degree top end. These hexabundles are bundles of fibres that are packed in a regular hexagonal array. They are built in sizes of 37, 61, 91, 127, and 169 fibres. The distribution of sizes of hexabundles was calculated to maximize the efficiency of the galaxy survey. The Hector hexabundles have been optimized for this instrument. Their regular hexagonal packing has been developed to improve data reduction accuracy, and the fibres have had a short length of their cladding etched in order to pack them as tightly as possible without reducing the optical quality of the devices.
Orbital angular momentum (OAM) beams, have attracted great attention in recent years. An OAM beam... more Orbital angular momentum (OAM) beams, have attracted great attention in recent years. An OAM beam with a phase singularity is characterized by a helical phase front which provides an additional degree of freedom for wide amount of classical and quantum optical applications. However, despite many attempts to generate and manipulate OAM beams, a robust, reliable and scalable technique to directly address generation, multiplexing and low-loss transmission of the distinct OAM beams is still in great demand. Here, we review the development of all-fiber, ring core photonics lantern mode multiplexer to generate high quality OAM beams up to the second order within a broad spectral range of >550 nm. Our device is a 5-mode mode selective photonic lantern (MSPL) with an annular refractive index profile which is fully compatible with well-established ring core and vortex transmission fibers. Through the excitation of pairs of degenerate linearly polarized (LP) modes of the MSPL, we demonstra...
We experimentally demonstrate a transverse mode-selective fiber laser using a photonic lantern. T... more We experimentally demonstrate a transverse mode-selective fiber laser using a photonic lantern. The output modes of laser are switchable among the 6 LP modes supported by the gain fiber. Their slope efficiency, optical spectra, and mode profiles are measured. Introduction Large mode-area optical fiber can support highorder of linear polarization (LP) modes. There are many motivations for producing high-order transverse modes of laser radiation. For example, it has been shown that high-order LP modes have higher threshold for detrimental nonlinear loss processes, such as stimulated Brillouin scattering (SBS), in comparison with the fundamental mode. It has also been shown that high-order modes can reduce the sensitivity to mode profile distortion and improve energy extraction in pulse laser systems. In fiber sensor systems, high-order LP modes in few mode fiber (FMF) allow for increasing the measurement sensitivity of fiber bending. Recent research also indicate that specific laser b...
Increasing concern for the ongoing availability and efficacy of herbicides is driving interest in... more Increasing concern for the ongoing availability and efficacy of herbicides is driving interest in the development of alternative physical and thermal weed control methods. Fortunately, improvements in weed detection through advancements in computing hardware and deep learning algorithms are creating an opportunity to use novel weed control tools, such as lasers, in large-scale cropping systems. For alternative control options, there are two key weed control timing opportunities, early and late post-crop emergence. Weed density for the early timing is typically higher, with a shorter window for control. Conversely, late post-emergent treatment of surviving and late-emerging weeds would occur in lower densities of larger and more variably sized weeds, given a prior weed control effort, but with a longer available weed control period. Research in laser weeding to date has primarily focused on early growth stage weeds and the ability of this approach to control larger weeds remains unkn...
Asia Communications and Photonics Conference 2015, 2015
3D printing of optical fibre preforms is reported. Tens of meters of air-structured optical fibre... more 3D printing of optical fibre preforms is reported. Tens of meters of air-structured optical fibre made from a propriety combination of acrylonitrile butadiene styrene (ABS) and polystyrene is drawn. Propagation losses better than α < 1.5 dB/cm @ 632 nm, α < 0.75 dB/cm @ 1064 nm, and α < 1.51 dB/cm @ 1550 nm are obtained. This work signals a milestone in the history of optical fibre manufacturing, further revolutionised by future 3D printing of materials such as silica and other glasses as well as sapphire and the like.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT Mode convertors couple light from one fibre mode to another. They have applications in d... more ABSTRACT Mode convertors couple light from one fibre mode to another. They have applications in dispersion compensation, nonlinear optics and atom guiding for example. We demonstrate coupling from the fundamental LP01 mode to the circularly symmetric TE01 mode, which has applications for atom guidance.
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
Transitions in core shape are formed in photonic crystal fibres by differential pressurisation of... more Transitions in core shape are formed in photonic crystal fibres by differential pressurisation of the holes and localised heating. Low-loss anamorphic transitions to rectangular and annular cores are formed, and improved coupling from diode lasers to fibres thereby demonstrated.
(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005
Tapering of conventional and photonic crystal fibres can be used to make glass-air waveguides dow... more Tapering of conventional and photonic crystal fibres can be used to make glass-air waveguides down to submicron scales, and gives them ready-made low-loss interfaces to simplify input and output coupling.
ABSTRACT New methods have been developed in post-processing and tapering of PCFs to achieve a var... more ABSTRACT New methods have been developed in post-processing and tapering of PCFs to achieve a variety of low-loss optical devices. Interfacing between waveguides with very different properties and highly efficient mode convertors are presented.
2007 9th International Conference on Transparent Optical Networks, 2007
ABSTRACT We have used tapering of photonic crystal fibres to make all-fibre mode converters for t... more ABSTRACT We have used tapering of photonic crystal fibres to make all-fibre mode converters for the LP11 and LP02 modes. The devices rely on adiabatic propagation rather than resonant coupling, allowing high extinction across a wide wavelength range.
ABSTRACT A miniature curvature wavefront sensor with a coherent fiber image bundle is proposed in... more ABSTRACT A miniature curvature wavefront sensor with a coherent fiber image bundle is proposed in which a miniature lateral displacement beamsplitter is designed to obtain the intra- and extra- focus images from a telescope simultaneously at its exit. The two images are received and relayed by two coherent fiber image bundles. The relayed images are then re-imaged to one camera and processed to obtain the input wavefront at telescope pupil. The whole device is quite compact and can be driven by a “Starbug” fiber positioning device currently under development within the Australian Astronomical Observatory. In this paper, the performance of the proposed sensor is investigated in details by applying a simulated atmospheric turbulence at the telescope pupil plane. We study the offset distance of two image measurement planes, fiber core size, fiber fill factor and the magnitude of natural guide star effects to its performance. This study provides guidance to the sensor design.
We describe two all-fiber devices for converting light from the fundamental mode to the second-or... more We describe two all-fiber devices for converting light from the fundamental mode to the second-order set of modes in optical fibers. The first is made by controlled hole collapse in a photonic crystal fiber, and the second is a twisted fused coupler made from few-moded conventional fiber. As well as having applications within fiber optics, the devices can be used to generate azimuthally polarized free-space beams.
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Papers by Sergio Leon-saval