PsiQuantum Records 1.2 dB Loss for Optical Switch

PsiQuantum has recorded a laboratory insertion loss of 1.2 dB for its new 8×8 optical switch, outperforming initial company targets while operating without integrated optical amplifiers. Tom’s Hardware Premium reported that the device achieves a crosstalk of 40 dB—meaning about 0.01% of light leaks to other ports—and a reconfiguration time of under 3 milliseconds.

Optical Performance Against Competitor Benchmarks

The 8×8 platform is strictly non-blocking, ensuring that new connections never disrupt ongoing transmissions and that every input reaches every output. PsiQuantum measures insertion loss fiber-to-fiber, which includes the light entering and exiting the chip but excludes connector losses. A paper published in Nature in 2025 reported that the company’s silicon nitride waveguides lose only 0.5 dB per meter, splitters lose 0.5 millidecibels, and crossings lose 1.2 millidecibels.

Competitors achieve varying loss metrics using different architectural approaches. Lumentum’s R300 switch, which features 300 ports, typically reaches around 1.5 dB at the start of its lifespan, according to a Lumentum switching general manager speaking to Gazettabyte. Salience Labs achieves insertion loss below 2 dB port-to-port for its OC-32M 32-port switch using built-in amplification, while iPronics offers an OC-32 platform with similar sub-300-microsecond reconfiguration claims. Google’s MEMS mirror-based switch, Palomar, also stays below 2 dB while managing 136 ports.

Integration Constraints and Data Center Deployment

The tolerable insertion loss depends heavily on the optics deployed at the end of each link. Coherent noted that optical circuit switches can add up to 3 dB of additional insertion loss, though their transceiver modules operate effectively under those conditions. Lumentum confirmed that a 3 dB loss threshold supports off-the-shelf FR4, DR4, and DR8 plug-in modules used to connect server GPUs and switches across distances ranging from 500 meters to 2 kilometers. PsiQuantum designed its 8×8 switch specifically for the O-band wavelengths utilized by these standard datacenter modules.

Semafor reported that PsiQuantum requires an insertion loss below 2 to 3 dB for market viability, placing its prototype well beneath Nvidia’s 3 dB request-for-proposals target. While the 8×8 prototype functions primarily as a demonstration vehicle, PsiQuantum has already taped out a 64×64 version, with a 72×72 model currently in development.

Silicon Photonics Roadmap and Future Speeds

Speed remains secondary to insertion loss for current optical circuit switch deployments. Google operates tens of thousands of switches to resize Tensor Processing Unit pods or reroute traffic around failed chips, tasks well-suited to millisecond-scale MEMS devices. PsiQuantum’s sub-3-millisecond reconfiguration falls into this operational class, though amplified chip switches from Salience and iPronics claim speeds under 300 microseconds to allow network rewiring during active workloads.

To achieve higher speeds, PsiQuantum utilizes barium titanate (BTO) in place of lithium niobate for its 64-port switches, enabling gigahertz-rate optical switching. While the initial 8×8 demonstration vehicle relies on thermal switching, BTO serves as an advanced path for future products.

Nvidia participates through its venture arm, NVentures, collaborating with PsiQuantum on GPU-QPU integration and silicon photonics, while also contributing to a $125 million funding round for iPronics in September.

Frequently Asked Questions About PsiQuantum Optical Switches

How does PsiQuantum’s 8×8 switch handle light leakage?

The device achieves a crosstalk of 40 dB, meaning approximately 0.01% of light leaks to adjacent ports during operation.

What materials are used to increase switching speeds in larger models?

PsiQuantum employs barium titanate (BTO) for its 64-port switches to shift light via voltage application at gigahertz rates, serving as an alternative to the thermal switching used in the 8×8 prototype.

How do competitor port counts compare to PsiQuantum’s current prototype?

PsiQuantum’s prototype features 8 ports, trailing commercial offerings such as Salience Labs at 32 ports, Google Palomar at 136 ports, and Lumentum at 300 ports.

More on this story: UC San Diego engineers develop optical switching technique