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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Second harmonic generation in nonlinear materials can be greatly enhanced byrealizing doubly-resonant cavities with high quality factors. However,fulfilling such doubly resonant condition in photonic crystal (PhC) cavities isa long-standing challenge, because of the difficulty in engineering photonicbandgaps around both frequencies. Here, by implementing a second-harmonic boundstate in the continuum (BIC) and confining it with a heterostructure design, weshow the first doubly-resonant PhC slab cavity with $2.4\times10^{-2}$ W$^{-1}$conversion efficiency under continuous wave excitation. We also report theconfirmation of highly normal-direction concentrated far-field emission patternwith radial polarization at the second harmonic frequency. These resultsrepresent a solid verification of previous theoretical predictions and acornerstone achievement, not only for nonlinear frequency conversion but alsofor vortex beam generation and prospective nonclassical sources of radiation.

Doubly resonant second-harmonic generation of a vortex beam from a bound state in the continuum