lithium niobate / 06 Devices / 6.11
6.11 Thin-film lithium tantalate: the sibling platform
L1 Phenomenon
Lithium tantalate is LN's closest relative: same structure, tantalum in place of niobium. LT wafers are already made in high volume for phone filters. In the eo-modulator-atlas sample (233 papers), thin-film LT modulators reach the same median voltage-length product as LN (2.43 vs 2.44 V cm), and in one paired comparison an LT modulator drifted less under a DC bias than its LN twin reported.
L2 Devices and values
| Fact | Value | Source |
|---|---|---|
| LT PICs by wafer bonding, SOI-compatible | 5.6 dB/m loss (DUV stepper); MZM VπL 1.9 V cm up to 40 GHz; lower birefringence than LN | reported |
| High-speed TFLT MZM | 110 GHz; 176 GBd PAM8, > 400 Gb/s net | reported |
| DC stability vs TFLN | < 1 dB (TFLT) vs 5 dB (TFLN) output fluctuation at quadrature over 46 h, 12.1 dBm input; VπL 3.4 V cm; 0-70 C operation | reported |
| TFLT bandwidth + drift | > 67 GHz, VπL 2.4 V cm, < 1 dB drift over 60 min | reported |
| High-temperature operation (TFLT, not TFLN) | waveguide and resonant modulators DC-bias stable at 120 C; EO modulation and bandwidth unaffected | reported (Al Sayem et al., arXiv 2604.27285) |
| Highest line rate in the eo-modulator-atlas sample (any platform) | 768 Gb/s line, 536 Gb/s net; highest symbol rate in the paper 226 GBd; C band, Vπ 1.35 V, > 110 GHz, 18 mm | reported (OFC 2026 Th4A.2) |
| O band, about 1 V (title: "Sub-V-driven") | Vπ 1.089 V average, range 1.045-1.166 V (10 Hz-10 kHz), > 110 GHz, 15 mm | reported (OFC 2026 W1A.4) |
| WDM transmitter | 1.6 Tb/s aggregate net | reported |
| EO comb | > 450 nm span, > 2,000 lines | reported |
| Atlas sample | TFLT papers per year: 4 (2024), 4 (2025), 14 (2026); median telecom push-pull VπL 2.43 V cm (n = 17) vs TFLN 2.44 (n = 66) | derived |
TFLT concentration: 22 TFLT papers in the atlas; EPFL on 9, KIT on 7 derived.
L3 Caveats
- The lower photorefraction / DC drift of LT is argued in papers; no dataset-wide drift comparison exists; Powell 2024 is one paired comparison under stated conditions.
- PPLT coercive field about 4x that of MgO:LN (Kuznetsov, Li, Kippenberg, arXiv 2512.07968) reported.
Sources
| Ref | Title | Link |
|---|---|---|
| Al Sayem | Stable thin-film lithium tantalate modulators operating at high temperature for uncooled operation | arxiv.org/abs/2604.27285 |
| Chen et al. 2026 | Thin-film lithium tantalate electro-optic modulator with balanced bandwidth-voltage and low DC drift | doi:10.1364/oe.595937 |
| Hulyal et al. 2026 | A 1.6 Tbit/s WDM Integrated Photonic IMDD Transmitter on Thin-Film Lithium Tantalate | doi:10.1364/cleo_si.2026.sth1f.2 |
| Kuznetsov et al. 2025 | Watt-level second harmonic generation in periodically poled thin-film lithium tantalate | arxiv.org/abs/2512.07968 |
| Powell et al. 2024 | DC-stable electro-optic modulators using thin-film lithium tantalate | doi:10.1364/oe.538870 |
| Wang et al. 2024 | Lithium tantalate photonic integrated circuits for volume manufacturing | doi:10.1038/s41586-024-07369-1 |
| Wang et al. 2024 | Ultrabroadband thin-film lithium tantalate modulator for high-speed communications | doi:10.1364/OPTICA.537730 |
| Zhang et al. 2025 | Ultrabroadband integrated electro-optic frequency comb in lithium tantalate | doi:10.1038/s41586-024-08354-4 |