Optomechanics with one-dimensional gallium phosphide photonic crystal cavities

Katharina Schneider, Yannick Baumgartner, Simon Hönl, Pol Welter, Herwig Hahn, Dalziel J. Wilson, Lukas Czornomaz, Paul Seidler

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Gallium phosphide offers an attractive combination of a high refractive index (n > 3 for vacuum wavelengths up to 4 µm) and a wide electronic bandgap (2.26 eV), enabling optical cavities with small mode volumes and low twophoton absorption at telecommunication wavelengths. Heating due to strongly confined light fields is therefore greatly reduced. Here, we investigate the benefits of these properties for cavity optomechanics. Utilizing a recently developed fabrication scheme based on direct wafer bonding, we realize integrated one-dimensional photonic crystal cavities made of gallium phosphide with optical quality factors as high as 1.1 × 105.We optimize their design to couple the optical eigenmode at ~200 THz via radiation pressure to a co-localized mechanical mode with a frequency of 3 GHz, yielding sideband-resolved devices. The high vacuum optomechanical coupling rate (g0 = 2φ × 400 kHz) permits amplification of the mechanical mode into the so-called mechanical lasing regime with input power as low as ~20 µW. The observation of mechanical lasing implies a multiphoton cooperativity of C > 1, an important threshold for the realization of quantum state transfer protocols. Because of the reduced thermo-optic resonance shift, optomechanically induced transparency can be detected at room temperature even in non-sideband-resolved devices in addition to the normally observed optomechanically induced absorption. Considering that GaP is also piezoelectric, these results establish GaP as an attractive material for future electro-opto-mechanical systems.

Original languageEnglish (US)
Article number354512
Pages (from-to)577-584
Number of pages8
Issue number5
StatePublished - May 20 2019
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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