Article

Ultrafast Laser Inscription of a 121-Waveguide Fan-Out for Astrophotonics

Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
Optics Letters (Impact Factor: 3.18). 06/2012; 37(12):2331-3. DOI: 10.1364/OL.37.002331
Source: PubMed

ABSTRACT Using ultrafast laser inscription, we report the fabrication of a prototype
three-dimensional 121-waveguide fan-out device capable of reformatting the
output of a 120 core multicore fiber (MCF) into a one-dimensional linear array.
When used in conjunction with an actual MCF, we demonstrate that the
reformatting function using this prototype would result in an overall
throughput loss of approximately 7.0 dB. However, if perfect coupling from the
MCF into the fan-out could be achieved, the reformatting function would result
in an overall loss of only approximately 1.7 dB. With adequate development,
similar devices could efficiently reformat the output of so-called "photonic
lanterns" fabricated using highly multicore fibers.

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    • "To make a photonic lantern we need a process for merging several single-mode cores into one multimode (MM) core, or (equivalently) splitting one multimode core into several single-mode (SM) cores. To date this has usually been achieved in two broad ways: by post-processing several single-mode fibre (SMF) cores to form a multimode fibre (MMF) core, with some kind of low-index jacket providing the multimode cladding [1] [3] [5] [7] [8] [12] [15] [18] [21] [22] [25] [37] [47] [48] [52] [53] [58] [59] [60] [76] [78]; or by direct ultrafast laser inscription of a pattern of waveguides into an integrated-optic chip [4] [13] [17] [19] [24] [27] [30] [35] [38] [40] [50] [54] [56] [57] [62] [63] [71] [74] [79]. In Section 2.1 we review the fibre tapering process, which is the key process by which most fibre lanterns have been made. "
    Conference Paper: The Photonic Lantern
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    ABSTRACT: Photonic lanterns are made by adiabatically merging several single-mode cores into one multimode core. They provide low-loss interfaces between single-mode and multimode systems where the precise optical mapping between cores and individual modes is unimportant.
    CLEO: Science and Innovations; 06/2014
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    • "The first demonstrations of using ultrashort pulses of light to inscribe 3D refractive index structures inside transparent materials were made in 1996 in two seminal papers [8][9]. Since then, the technique has rapidly developed, and is now finding applications in areas ranging including microsystems [10], biophotonics [11], waveguide lasers/amplifiers [12][13] and now astrophotonics for the development of multimode-to-single-mode integrated photonic lanterns [1], integrated beam combiners for long-baseline interferometry [2], 3D fan-out devices [3] and integrated optical waveguide pupil remappers [14]. "
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    ABSTRACT: Ultrafast laser inscription (ULI) is a rapidly maturing technique which uses focused ultrashort laser pulses to locally modify the refractive index of dielectric materials in three-dimensions (3D). Recently, ULI has been applied to the fabrication of astrophotonic devices such as integrated beam combiners, 3D integrated waveguide fan-outs and multimode-to-single mode convertors (photonic lanterns). Here, we outline our work on applying ULI to the fabrication of volume phase gratings (VPGs) in fused silica and gallium lanthanum sulphide (GLS) glasses. The VPGs we fabricated had a spatial frequency of 333 lines/mm. The optimum fused silica grating was found to exhibit a first order diffraction efficiency of 40 % at 633 nm, but exhibited approximately 40 % integrated scattered light. The optimum GLS grating was found to exhibit a first order diffraction efficiency of 71 % at 633 nm and less than 5 % integrated scattered light. Importantly for future astronomy applications, both gratings survived cooling to 20 K. This paper summarises the grating design and ULI manufacturing process, and provides details of the diffraction efficiency performance and blaze curves for the VPGs. In contrast to conventional fabrication technologies, ULI can be used to fabricate VPGs in almost any dielectric material, including mid-IR transmitting materials such as the GLS glass used here. Furthermore, ULI potentially provides the freedom to produce complex groove patterns or blazed gratings. For these reasons, we believe that ULI opens the way towards the development of novel VPGs for future astronomy related applications.
    Proceedings of SPIE - The International Society for Optical Engineering 07/2012; DOI:10.1117/12.926108 · 0.20 Impact Factor
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    • "The Wgs are fabricated by an ultrafast ultrashortpulse laser-writing process which enables the incorporation of the optical circuits into any other instrument device or substrate, as far as the material optical absorption band edge is below the laser wavelength, and without requiring any lithography or clean room facility [1]. With the 3D DLW technique the as-fabricated Wgs typically have average propagation losses in the 0.5 dB/cm range, the Wg cores can be sized and tailored in index contrast to match the specific numerical aperture or modality of connecting fibers, and more importantly, they can be spatially positioned at will inside the sample, therefore giving free access to new refractive-index topologies which were formerly impossible with planar fabrication techniques, and allowing to create photonic devices with unique optical properties which open up the range of imaginable designs, such as photonic lanterns [2] or complex evanescent coupling schemes with before unforeseen properties [3]. Figure 1. 3D 3-Telescope Beam Combiner for the N-Band. "
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    ABSTRACT: We present here our recent progress in the three-dimensional (3D) direct laser writing (DLW) of step-index core waveguides inside diverse technologically relevant dielectric substrates, with specific emphasis on the demonstration of DLW mid-infrared waveguiding in the whole transparency range of these materials.
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