Underwater is still a "Communication Dead Zone"
Let's connect it with light.
Welcome to the Kazuhiko Nakamura Lab at the Faculty of Engineering,
University of Yamanashi.
Would you like to explore the world of "Underwater Optical Wireless Communication,"
a future communication technology?
Why go underwater?
Underwater, where Wi-Fi and mobile signals can't reach, there's an "invisible wall" blocking communication.
Radio waves cannot penetrate.
Water quickly absorbs the energy of radio waves. Just like running through thick mud, radio waves can't travel more than a few meters underwater.
Sound is too slow.
Sound (audible sound, ultrasound) can travel far, but its communication speed is very "slow." Sending high-quality video is like mailing a movie frame by frame, which can't keep up with modern demands.
Communicating data with Light! Future Technology
With ultra-high-speed blinking of lasers and LEDs, vast amounts of information can be transmitted instantly.
Compare underwater communication
Switch between the buttons below to see the performance differences of radio, acoustic, and optical waves.
(May vary slightly depending on water quality)
Why use blue and green light?
Water has a "window" of wavelengths (colors) that allows light to pass through easily. Red light is absorbed quickly, but blue and green light can travel far.
However, this can also change depending on water quality.
(The graph below is an example)
The Future of the Ocean will Drastically Change
This technology will make previously impossible things possible, enriching our lives and society.
Deep Sea Exploration & Science
Observe unknown creatures and underwater volcanoes in real-time and high-definition. Challenge the mysteries of Earth's last frontier.
Environmental Monitoring
Continuously monitor water quality and ecosystems. Protect the health of the ocean and achieve sustainable fisheries.
Infrastructure Inspection & Disaster Prevention
Underwater drones safely inspect bridges and dams. Contribute to rapid situation assessment during disasters.
Industry & Leisure
Video calls while diving. New forms of entertainment and tourism will emerge.
Research Style
The scientific adventure of bringing ideas to life is an endless cycle.
1. Conception & Hypothesis
Everything begins with curiosity: "Why?" and "What if?" We identify problems to solve and predict their answers.
2. Theoretical Construction
This stage involves modeling new communication mechanisms, modulation formats, and signal processing techniques, creating a "blueprint" for how they will function.
3. Simulation
We create a "virtual communication system" within a computer to test the "blueprint," refining it without incurring significant costs.
We primarily use Matlab (GNU Octave) (and occasionally Python, C).
4. Prototyping
Based on the insights gained from simulations, we build actual working transceivers. This is the moment when an idea takes "physical form" for the first time.
5. Verification Experiment
First, using a lab tank, we conduct the most crucial tests to verify if the idea works in the real world. In the future, this will extend to actual oceans, lakes, and rivers.
We possess equipment and facilities for gigabit-class optical wireless communication experiments using visible light semiconductor lasers and LEDs.
6. Feedback
We analyze the experimental results to identify new questions and areas for improvement. These discoveries then lead to the next "conception and hypothesis."
Current Challenge: Delivering Light Through Turbid Water
The biggest challenge is "turbidity." Many socially important application sites, such as ports and rivers, have turbid water. In my lab, while cycling through this research process, we are investigating the potential of "yellow to orange" light, which has not received much attention until now, to enable high-speed communication even in turbid water.
Kazuhiko NAKAMURA, Associate Professor
You might wonder, "Why is a communication expert focusing on the ocean?" A vast and crucial part of our planet remains unconnected. My passion lies in bringing that "dead zone" online, building the technology to realize the "Underwater Internet of Things."
- Affiliation: Graduate School of Integrated Research and Education, University of Yamanashi, Faculty of Engineering, Department of Fundamental Sciences
- Center for Fundamental Education, Faculty of Engineering
- Concurrently appointed to the Electrical and Electronic Engineering Course, Department of Engineering
- Specialization: Communication and Network Engineering (especially Underwater Optical Wireless Communication)
- Degree: Ph.D. in Engineering
To Researchers and Companies
For details on academic papers and collaborative research, please refer to the university's researcher database.
To Researcher Database PageTo students aspiring to be future researchers
The adventure begins with "Why?". Can you turn that curiosity into the "power" to solve global problems?
The Faculty of Engineering at the University of Yamanashi awaits your challenge.