Standard fiber achieves world record bandwidth, exceeding total global Internet traffic
A research team at the National Institute of Information and Communications Technology (NICT) Network Research Institute in Japan has achieved a new world record for bandwidth on a standard diameter optical fiber - 1.53 Pbit/s. This means that global Internet traffic can be packed into it.
Half a month ago, PhotonBox reported a similar advance: a bandwidth of 1.84 Pbit/s was achieved using only a single laser and a single optical chip, which is a higher value than NICT achieved, but it had the problem of using a photonic chip that was still in the experimental design phase; therefore, this NICT research may be deployed much faster.
01Multiplexing technology: achieving a record bandwidth of 1.53 Pbit/s
By encoding information at 55 different optical frequencies (a technique known as multiplexing), the researchers achieved a bandwidth of about 1.53 Pbit/s. This is enough bandwidth to carry the entire world's Internet traffic (estimated at less than 1 Pbit/s) over a single fiber optic cable: a million times more effective than the Gbit connection (in the best case scenario) that we have in the average person.
The technology works by using different frequencies of light across the spectrum. Since each "color" of the spectrum (visible and invisible light) has its own frequency: unlike all other frequencies, it can carry its own separate stream of information. The researchers managed to unlock a spectral efficiency of 332 bits/s/Hz (bits per hertz per second); this is three times higher than their previous best attempt in 2019: which achieved a spectral efficiency of 105 bits/s/Hz.
Comparison of current results with NICT's past results
02Experimental setup: transmitting C-band information over 184 different wavelengths
The researchers managed to transmit C-band information over the entire 184 different wavelengths: these separate, non-overlapping frequencies were used to transmit information simultaneously within the fiber optic cable. Before being sent over the fiber optic cable, the light is modulated to transmit 55 separate data streams (modes). After modulation (as with most fiber optic cables deployed today), it takes a glass core to transmit all of the data. As data is sent (across 184 wavelengths and 55 modes), the receiver decodes the different wavelengths and modes to collect their data. In the experiment, the distance between the sender and the receiver was set to 25.9 km.
Schematic diagram of the newly developed transmission system. ①Light comb source: 184 carriers are generated in one light comb source. ②Signal modulation. The carriers are modulated with 16 QAM signals and polarization multiplexing is performed. ③Parallel signal generation. The signals of each mode are bifurcated and path delays are applied to simulate independent data streams. ④Mode multiplexer. Each signal is converted to a different spatial mode and launched into a 55-mode fiber. ⑤ 55-mode fiber. The signal is propagated in a 25.9 km long 55-mode fiber. ⑥Mode demultiplexer. The signal of each spatial mode at the receiver end is separated and converted into the basic mode. (vii) High-speed parallel receiver. The mode demultiplexed signals are wavelength demultiplexed by filters and converted into electrical signals by parallel coherent receivers. (viii) Offline signal processing. MIMO processing to eliminate signal interference during fiber propagation.
Left: conceptual diagram of cross-sectional and multimode propagation of a 55-mode fiber; Right: standard single-mode fiber
The experimental results show that, despite a slight drop in data rate at the long wavelength end of the C-band (near 1,565 nm), an almost uniform and stable data rate was obtained in the other wavelength regions, achieving a total of 1.53 Pbit/s after error correction.
03Promising deployment: long-range transmission capabilities will be further explored
Half a month ago, PhotonBox reported a similar advance: a bandwidth of 1.84 Pbit/s was achieved using only a single laser and a single optical chip, which is higher than the value achieved by NICT, but it had the problem of using a photonic chip that is still in the experimental design phase; therefore, this research by NICT may be deployed more quickly (it just needs to slowly upgrade the fiber infrastructure to adapt its design).
Japanese scholars also stated [2], "In the future, we will explore further transmission capabilities by expanding the frequency band and the underlying technologies needed for long-range transmission and network deployment."
[2]https://www.nict.go.jp/en/press/2022/11/10-1.html#kiji8
