Procuring high-speed optical chips for coherent transmission systems requires more than comparing peak data rates. As networks migrate to 800G and 1.6T ZR applications, the modulator’s electro-optic parameters directly determine link reach, power consumption, and signal integrity. Yet many sourcing teams focus narrowly on bandwidth while overlooking insertion loss, half-wave voltage, and extinction ratio—specifications that interact in complex ways. Drawing from our experience developing thin-film lithium niobate (TFLN) platforms, we have learned that a disciplined technical evaluation separates reliable suppliers from those delivering incomplete solutions. This guide outlines the critical metrics for sourcing TFLN chips and other optical chips for coherent pluggables.
Bandwidth and Insertion Loss: The Trade-Off You Cannot Ignore
For 800G and 1.6T ZR coherent modules, modulator bandwidth directly supports higher baud rates. The specification sheet may advertise 70 GHz bandwidth, but what matters is the flatness of the response and the accompanying insertion loss. In our TFLN chips designed for coherent PDMIQ applications, we achieve a 3 dB bandwidth of 70 GHz with insertion loss below 7 dB—including coupling loss. This combination is rare: many optical chips sacrifice several decibels of loss to reach similar bandwidth, forcing designers to boost laser power or add amplification. When evaluating optical chips, always request the loss‑bandwidth product measured under actual drive conditions. Low insertion loss (sub‑7 dB) preserves optical signal‑to‑noise ratio for long‑haul ZR links, while sufficient bandwidth (≥70 GHz) supports 96 GBaud and beyond.
Half‑Wave Voltage and Extinction Ratio: Power and Fidelity
Another pair of interdependent specifications is half‑wave voltage (Vπ) and DC extinction ratio (ER). Lower Vπ means the modulator can be driven by CMOS‑compatible voltages, reducing power consumption and eliminating the need for expensive driver amplifiers. Our TFLN chips achieve a differential Vπ below 4.5 V, enabling direct drive from 3.3 V logic while maintaining a DC‑ER above 25 dB. High extinction ratio is essential for coherent systems to suppress carrier leakage and improve modulation depth. When sourcing optical chips, verify that the Vπ specification is differential and measured at the operating baud rate. Some suppliers quote single‑ended Vπ that doubles in differential mode, misleading procurement teams. For 800G ZR and 1.6T applications, demand Vπ < 5 V differential and ER > 20 dB across temperature.
Making an Informed Sourcing Decision
Beyond individual specifications, consider consistency across batches and the supplier’s design‑to‑packaging capability. TFLN chips have matured from research devices to production‑ready components, but not all vendors offer the same level of manufacturing control. We have established platforms for next‑generation TFLN‑based PIC design, fabrication, and packaging, capable of mass production and delivery. This ensures that the optical chips you qualify today will match those shipped in volume.
At Liobate, we are committed to providing superior TFLN chips and optical chips for coherent 800G/1.6T ZR modules, data centers, telecom networks, and test instruments. We invite procurement and engineering teams to evaluate our 70 GHz PDMIQ modulator chips with <7 dB loss and <4.5 V Vπ. Let us help you source with confidence.
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