English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The characterisation of loss in optical waveguides is essential inunderstanding the performance of these devices and their limitations. Whilstinterferometric-based methods generally provide the best results for low-losswaveguides, they are almost exclusively used to provide characterization incases where the waveguide is spatially single-mode. Here, we introduce aFabry-P\'erot-based scheme to estimate the losses of a nonlinear (birefringentor quasi-phase matched) waveguide at a wavelength where it is multi-mode. Themethod involves measuring the generated second harmonic power as the pumpwavelength is scanned over the phasematching region. Furthermore, it is shownthat this method allows one to infer the losses of different second harmonicspatial modes by scanning the pump field over the separated phase matchingspectra. By fitting the measured phasematching spectra from a titaniumindiffused lithium niobate waveguide sample to the model presented in thispaper, it is shown that one can estimate the second harmonic losses of a singlespatial-mode, at wavelengths where the waveguides are spatially multi-mode.

An interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation