So Fast, It’s Unreal: Japan’s Internet Can Download All of Netflix in One Second
July 12, 2025

Imagine being able to download every HD video on Netflix in just one second… Now, with Japan, we can say yes.

Japan’s National Institute of Information and Communications Technology (NICT) achieved a world-record internet data transmission speed of 1.02 petabits per second (Pbps) in a lab setting.

What Actually Happened

Achieved using a newly developed standard 19-core optical fibre, equivalent to 19 standard fibres, low loss across multiple wavelength bands, and the development of an optical amplification relay function compatible with this fibre.
19-core optical fiber, Source: NICT

1.02 Pbps = 1,020,000 Gbps 



We know that standard fibre is single-core, which limits the speed — it usually maxes out at around 80–100 km on high frequencies, such as the C-Band and L-Band, which operate in the THz range. However, in this experiment, they utilised multi-core fibre, which has 19 cores — that’s 19 times more than a single-core fibre — and employed 180 wavelengths in the L & C bands, along with 16QAM as the modulation technique. 

What Are the C and L Bands?

  • C-Band
    • Frequency Range: 191.5–195.5 THz
    • Wavelength Range: 1530–1565 nm
  • L-Band
    • Frequency Range: 185–191.5 THz
    • Wavelength Range: 1565–1625 nm

In the Japanese NICT experiment:

  • They transmitted 180 wavelengths (channels) using both bands.
  • This dramatically increased the total bandwidth and data rate.
  • The use of dense wavelength-division multiplexing (DWDM) in both bands allowed parallel transmission streams on a single fibre.
 
Transmission loss characteristics of a coupled 19-core optical fiber and generated C-band and L-band optical signals, Source: NICT

The speed reached 6.2 terabits per second on the L-band and 6.7 terabits per second on the C-band, for a total of approximately 1.02 petabits per second.



Using both C-band and L-band is like adding extra lanes to a fibre-optic highway, allowing far more data to travel simultaneously, which is key to breaking petabit-per-second speed records.

How can this speed be beneficial in 6G?

The 1.02 Pbps fibre-optic speed breakthrough can be highly beneficial to the development and performance of 6G networks, especially in terms of backhaul, core network capacity, and future-facing applications.

1. Massive Backhaul Capacity for 6G

  • 6G will push data rates up to 1 Tbps per user (theoretically), far beyond 5G.
  • To support such speeds across millions of devices, the fibre-optic backhaul (between base stations and the core network) must scale up drastically.
  • Petabit-scale links can ensure no bottlenecks between:
    • RAN (Radio Access Network)
    • Edge data centres
    • Core/Transport networks

2. Support for Future Applications

  • Holographic Communication, which requires 4–5 Tbps per session. 
  • Real-time XR/VR Metaverse, which requires continuous multi-Gbps streams per user.
  • Autonomous Swarm Robotics requires millisecond latency and a huge volume of telemetry data.
  • Digital Twins require Real-time updates from sensors, cameras, and other devices.
 
 

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