Integrated photonic building blocks for nextgeneration astronomical instrumentation I: The multimode waveguide

Nemanja Jovanovic*, Izabela Spaleniak, Simon Gross, Michael Ireland, Jon S. Lawrence, Christopher Miese, Alexander Fuerbach, Michael J. Withford

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)
15 Downloads (Pure)


We report on the fabrication and characterization of composite multimode waveguide structures that consist of a stack of single-mode waveguides fabricated by ultrafast laser inscription. We explore 2 types of composite structures; those that consist of overlapping single-mode waveguides which offer the maximum effective index contrast and nonoverlapped structures which support multiple modes via strong evanescent coupling. We demonstrate that both types of waveguides have negligible propagation losses (to within experimental uncertainty) for light injected with focal ratios >8, which corresponds to the cutoff of the waveguides. We also show that right below cutoff, there is a narrow region where the injected focal ratio is preserved (to within experimental uncertainty) at the output. Finally, we outline the major application of these highly efficient waveguides; in a device that is used to reformat the light in the focal plane of a telescope to a slit, in order to feed a diffraction-limited spectrograph.

Original languageEnglish
Pages (from-to)17029-17043
Number of pages15
JournalOptics Express
Issue number15
Publication statusPublished - 16 Jul 2012

Bibliographical note

This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: []. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

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