As_2S_3–silica double-nanospike waveguide for mid-infrared supercontinuum generation

Shangran Xie, Francesco Tani, John C. Travers, Patrick Uebel, Celine Caillaud, Johann Troles, Markus A. Schmidt, Philip St. J. Russell

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


A double-nanospike As2S3As2S3–silica hybrid waveguide structure is reported. The structure comprises nanotapers at input and output ends of a step-index waveguide with a subwavelength core (1 μm in diameter), with the aim of increasing the in-coupling and out-coupling efficiency. The design of the input nanospike is numerically optimized to match both the diameter and divergence of the input beam, resulting in efficient excitation of the fundamental mode of the waveguide. The output nanospike is introduced to reduce the output beam divergence and the strong endface Fresnel reflection. The insertion loss of the waveguide is measured to be ∼2  dB∼2  dB at 1550 nm in the case of free-space in-coupling, which is ∼7  dB∼7  dB lower than the previously reported single-nanospike waveguide. By pumping a 3-mm-long waveguide at 1550 nm using a 60-fs fiber laser, an octave-spanning supercontinuum (from 0.8 to beyond 2.5 μm) is generated at 38 pJ input energy.
Original languageEnglish
Article number213497
Pages (from-to)5216-5219
Number of pages4
JournalOptics Letters
Issue number17
Publication statusPublished - 1 Sept 2014


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