# Institute of Science Tokyo built a 320-µm silicon modulator reaching 200 Gb/s

- Published: 2026-11-07 04:19 UTC
- Section: Machines & Making › Electronics
- Tags: slow light modulator, silicon photonics, electro optic equalizer, Institute of Science Tokyo, photonic crystal waveguide, PAM4 200 Gbps
- URL: https://realtech.media/news/rt-3a332909ae12109f79b9346c_institute_of_science/

**A slow-light silicon photonic crystal modulator with an integrated electro-optic equalizer achieved 200 Gb/s data rates in prototype tests.**

![Institute of Science Tokyo built a 320-µm silicon modulator reaching 200 Gb/s](https://realtech.media/media/2026/11/c1dd4bf1570026d0.jpg)
*UC Davis College of Engineering, Wikimedia Commons, CC BY 2.0*

Researchers from the Institute of Science Tokyo, Yokohama National University, and the National Institute of Advanced Industrial Science and Technology demonstrated a compact silicon slow-light modulator with an integrated equalizer, according to nature.com [1]. The prototype features an active device length of 320 µm and is engineered to enhance data transmission bandwidth while minimizing energy consumption in optical interconnects [1].

## Built-in electro-optic equalization

Standard silicon Mach-Zehnder modulators often rely on millimeter-scale phase shifters, which exhibit bandwidth constraints below 50 GHz and require power-hungry digital signal processing to exceed 100 Gb/s per lane [1]. In contrast, the demonstrated architecture integrates a photonic crystal waveguide slow-light modulator with a built-in electro-optic equalizer [1]. By monolithically combining optical delay lines and optical crossings within segmented slow-light phase shifters, the team formed an on-chip feedforward response [1]. This structure produces a high-pass frequency response that directly compensates for the device's intrinsic roll-off, expanding the 3-dB electro-optic bandwidth beyond the Nyquist bandwidth required for high-speed operation [1].

## High-speed testing and low power consumption

Experimental testing of the fabricated 320-µm device showed that it can operate using low drive voltages compatible with fin field-effect transistor complementary metal-oxide-semiconductor technology [1]. Under on-off keying modulation, the modulator achieved a data rate of 140 Gb/s with an energy consumption of 26 fJ/bit [1]. Operating under four-level pulse amplitude modulation, the device achieved a transmission speed of 180 Gb/s without requiring any digital signal processing [1]. When tested with a low-complexity 11-tap digital equalizer, the data transmission rate reached 200 Gb/s [1]. The integrated feedforward design provides an approach for optical transceivers without relying on complex, nearly 100-tap digital equalizers or high-voltage standalone electrical drivers [1].

## Sources

1. [nature.com](https://www.nature.com/articles/s41467-026-78128-1)
2. [EurekAlert](https://www.eurekalert.org/news-releases/1150586)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-3a332909ae12109f79b9346c_institute_of_science/