Arrayed waveguide grating spectrometers for astronomical applications: new results.

One promising application of photonics to astronomical instrumentation is the miniaturization of near-infrared (NIR) spectrometers for large ground- and space-based astronomical telescopes. Here we present new results from our effort to fabricate arrayed waveguide grating (AWG) spectrometers for astronomical applications entirely in-house. Our latest devices have a peak overall of ∼23%, a spectral resolving power (λ/δλ) of ~1300, and cover the entire H band (1450-1650 nm) for Transverse Electric (TE) polarization. These AWGs use a silica-on-silicon platform with a very thin layer of Si3N4 as the core of the waveguides. They have a free spectral range of ~10 nm at a of ~1600 about wavelength nm and a contrast ratio or crosstalk of 2% (-17 dB). Various practical aspects of implementing AWGs as astronomical spectrographs are discussed, including the coupling of the light between the fibers and AWGs, high-temperature annealing to improve the throughput of the devices at ~1500 nm, cleaving at the output focal plane of the AWG to provide continuous wavelength coverage, and a novel algorithm to make the devices polarization insensitive over a broad band. These milestones will guide the development of the next generation of AWGs with wider free spectral range and higher resolving power and throughput.

[1]  S. D. Collins,et al.  Thick films of silicon nitride , 1990 .

[3]  J. Bowers,et al.  Passive technologies for future large-scale photonic integrated circuits on silicon: polarization handling, light non-reciprocity and loss reduction , 2012, Light: Science & Applications.

[4]  Wim Bogaerts,et al.  Silicon and silicon nitride photonic circuits for spectroscopic sensing on-a-chip [Invited] , 2015 .

[5]  T A Birks,et al.  Ultrafast laser inscription of an integrated photonic lantern. , 2011, Optics express.

[6]  Sergio G. Leon-Saval.  The Photonic Lantern , 2018 .

[7]  Joss Bland-Hawthorn,et al.  Development of high-resolution arrayed waveguide grating spectrometers for astronomical applications: first results , 2016, Astronomical Telescopes + Instrumentation.

[8]  I. Kymissis,et al.  Photonic crystal spectrometer. , 2010, Optics express.

[9]  D. Van Thourhout,et al.  Comparison of AWGs and Echelle Gratings for Wavelength Division Multiplexing on Silicon-on-Insulator , 2014, IEEE Photonics Journal.

[10]  N. Jovanovic,et al.  First starlight spectrum captured using an integrated photonic micro-spectrograph , 2012, 1208.4418.

[11]  Jessica R. Zheng,et al.  GNOSIS: THE FIRST INSTRUMENT TO USE FIBER BRAGG GRATINGS FOR OH SUPPRESSION , 2012, 1212.1201.

[12]  E. Irene.  Residual stress in silicon nitride films , 1976 .

[13]  Kang Xie,et al.  Dual-Core Photonic Crystal Fiber for Use in Fiber Filters , 2016, IEEE Photonics Journal.

[14]  Andrea M Armani,et al.  Low-loss silica-on-silicon waveguides. , 2011, Optics letters.

[15]  Robert J. Harris,et al.  Applications of Integrated Photonic Spectrographs in astronomy , 2012, 1210.5885.

[16]  Alexander Argyros,et al.  Photonic lanterns: a study of light propagation in multimode to single-mode converters. , 2010, Optics express.

[17]  J. Bland-Hawthorna,et al.  Instruments without optics : an integrated photonic spectrograph , 2006 .

[18]  T. Hashimoto,et al.  Loss Uniformity Improvement of Arrayed-Waveguide Grating With Mode-Field Converters Designed by Wavefront Matching Method , 2009, Journal of Lightwave Technology.

[19]  R. Salvaterra.  High redshift Gamma-Ray Bursts , 2015, 1503.03072.

[20]  Ivan Avrutsky,et al.  A simple miniature optical spectrometer with a planar waveguide grating coupler in combination with a plano-convex lens. , 2006, Optics express.

[21]  R. Kashyap.  Fiber Bragg Gratings , 1999 .

[22]  E. Rol,et al.  Low-resolution VLT spectroscopy of GRBs 991216, 011211 and 021211 , 2005 .

[23]  K. Oda,et al.  Transmission characteristics of arrayed waveguide N/spl times/N wavelength multiplexer , 1995 .

[24]  A. Leinse,et al.  Planar waveguides with less than 0.1 dB/m propagation loss fabricated with wafer bonding. , 2011, Optics express.

[25]  Mario Dagenais,et al.  Arbitrary on-chip optical filter using complex waveguide Bragg gratings , 2016 .

[26]  Y. Hibino,et al.  Polarization-insensitive arrayed-waveguide grating wavelength multiplexer on silicon. , 1992, Optics letters.

[27]  Nick Cvetojevic,et al.  Miniature spectrographs: characterization of arrayed waveguide gratings for astronomy , 2010, Astronomical Telescopes + Instrumentation.

[28]  Matthew Colless,et al.  Hector: a high-multiplex survey instrument for spatially resolved galaxy spectroscopy , 2012, Other Conferences.

[29]  J. Bowers,et al.  Low-loss Si3N4 arrayed-waveguide grating (de)multiplexer using nano-core optical waveguides. , 2011, Optics express.

[30]  J. Bland-Hawthorn,et al.  Instruments without optics: an integrated photonic spectrograph , 2006, SPIE Astronomical Telescopes + Instrumentation.

[31]  Nick Cvetojevic,et al.  Demonstration of uniform multicore fiber Bragg gratings. , 2014, Optics express.

[32]  Mk Meint Smit,et al.  PHASAR-based WDM-devices: Principles, design and applications , 1996 .

[33]  C. Henry,et al.  Low loss Si(3)N(4)-SiO(2) optical waveguides on Si. , 1987, Applied optics.

[34]  G. Meltz,et al.  Formation of Bragg gratings in optical fibers by a transverse holographic method. , 1989, Optics letters.

[35]  Jeremy Allington-Smith,et al.  Astrophotonic spectroscopy: defining the potential advantage , 2009, 0910.4361.

[36]  Nick Cvetojevic,et al.  Developing arrayed waveguide grating spectrographs for multi-object astronomical spectroscopy. , 2012, Optics express.

[37]  Joss Bland-Hawthorn,et al.  Astrophotonics: a new era for astronomical instruments. , 2009, Optics express.

[38]  Joris Van Campenhout,et al.  Silicon-based heterogeneous photonic integrated circuits for the mid-infrared , 2013 .

[39]  Yingbai Yan,et al.  Design of flat-field arrayed waveguide grating with three stigmatic points , 2003 .

[40]  A. Leinse,et al.  Ultra-low-loss high-aspect-ratio Si3N4 waveguides. , 2011, Optics express.