lithium niobate / 06 Devices / 6.8
6.8 Acousto-optic and optomechanical devices
L1 Phenomenon
LN is piezoelectric: a voltage on comb-shaped electrodes launches a sound wave across the chip. The sound wave strains the crystal, which changes its refractive index, so a gigahertz sound wave can modulate or frequency-shift light.
Interdigital transducer and SAW, top view, 14 px per µmsingle-electrode IDT, finger width λ/4
λac 1.989 µmIDT period (pitch) 1.989 µmfinger 0.497 µmv 3978.4 m/s
Cut
λ = v/f. v: free-surface SAW velocity of the cut from the partial-wave solver with the Kushibiki 1999 constants derived (solver: chapter 03). Crests drawn qualitatively; the photoelastic index change follows the strain sign.
Cut
- Acoustic wavelength = IDT period
- 1.989 µm
- Finger width
- 0.497 µm
- SAW velocity
- 3978.4 m/s
Doubling the frequency halves the finger pitch on screen (fixed 18 px per µm). Single-electrode IDT, finger width λ/4; λ = v/f with the free-surface SAW velocity of the cut from the partial-wave solver and the Kushibiki 1999 constants derived (solver: chapter 03). Crests drawn qualitatively; the photoelastic index change follows the strain sign.
L2 Devices and values
| Device | Value | Source |
|---|---|---|
| Suspended TFLN AO modulator, room temperature | up to 4.5 GHz; Vπ 0.77 V (racetrack); g0/2π 1.1 kHz | reported |
| LN optomechanical crystal | g0/2π about 120 kHz; phonon lasing | reported |
| AO modulator, LN on sapphire | first unsuspended devices | reported |
| AO modulator, TFLN + chalcogenide, unsuspended | VπL 0.03 V cm | reported |
| AO frequency shifter | 3 GHz, > 30 dB carrier suppression | reported |
| LN phononic resonator + superconducting qubit | phonon-number splitting about 5x qubit linewidth | reported |
| Entangled mechanical resonators (LN) | state tomography | reported |
L3 Unverified values and units
- M2 of LN: no primary value is available (the Uchida and Niizeki compilation value is unverified).
- AO VπL (acoustic drive) and EO VπL (Pockels drive) share a unit but not a mechanism; they are not comparable.
Sources
| Ref | Title | Link |
|---|---|---|
| Arrangoiz-Arriola et al. 2019 | Resolving the energy levels of a nanomechanical oscillator | doi:10.1038/s41586-019-1386-x |
| Jiang et al. 2019 | Lithium niobate piezo-optomechanical crystals | doi:10.1364/OPTICA.6.000845 |
| Kushibiki et al. 1999 | Accurate measurements of the acoustical physical constants of LiNbO/sub 3/ and LiTaO/sub 3/ single crystals | doi:10.1109/58.796136 |
| Sarabalis et al. 2020 | Acousto-optic modulation in lithium niobate on sapphire | doi:10.1063/5.0012288 |
| Shao et al. 2019 | Microwave-to-optical conversion using lithium niobate thin-film acoustic resonators | doi:10.1364/OPTICA.6.001498 |
| Shao et al. 2020 | Integrated microwave acousto-optic frequency shifter on thin-film lithium niobate | doi:10.1364/OE.397138 |
| Wan et al. 2022 | Highly efficient acousto-optic modulation using nonsuspended thin-film lithium niobate-chalcogenide hybrid waveguides | doi:10.1038/s41377-022-00840-6 |
| Wollack et al. 2022 | Quantum state preparation and tomography of entangled mechanical resonators | doi:10.1038/s41586-022-04500-y |