Senior Distinguished Researcher
Kazuhide Nakajima
Research on optical fiber technology for realizing continuous advances in optical communication infrastructure
Senior Distinguished Researcher
Kazuhide Nakajima
--Please tell us about the research fields, research projects, and research themes that you are currently engaged in.
Since entering NTT, I have been engaged in the research of optical fiber technologies.
Looking back, the 1980s saw the introduction of the first optical transmission system running through the Japanese archipelago, and since then, the deployment of optical fiber has extended as far as mobile-terminal base stations and individual households. Today, we are usually not conscious of optical fiber when accessing the Internet through our personal computers or smartphones, but optical fiber has nevertheless spread throughout the world as a physical infrastructure indispensable to our daily lives. I have been engaged in the research of technologies for the design, manufacture, and evaluation of optical fiber itself and have been actively involved in the international standardization of commercialized optical fiber technologies.
--Please give us some details on new optical fiber technologies that you are currently researching.
In the research of optical fiber, how to go about decreasing loss and increasing capacity are eternal issues. The data transmission capacity flowing through today's optical fiber network continues to increase vigorously at an annual rate of more than 10%, but looking ahead, there will be a need for technology that can increase the transmission capacity of current optical fiber by 100 to 1000 times or more. To this end, there has been much research throughout the world on multi-core optical fiber that bundles multiple optical paths (cores) within a single optical fiber. As part of these efforts, our research group has achieved multi-core optical fiber having a transmission capacity more than 100 times that of current optical fiber and the world's top space usage efficiency. For this achievement, we received a top-scoring evaluation at a leading international conference.
In addition, optical fiber has a transmission bandwidth greater than 50,000 times that of LAN (electrical) cable, which is equivalent to a transmission capacity of several dozen two-hour 8K movies in one second. However, today's optical fiber is capable of using only about one tenth of that potential for the reason that the transmission performance of optical fiber varies according to signal wavelength.
We have been a world leader in the research of photonic crystal fiber (PCF) having a large number of holes arranged across the cross sectional area of the optical fiber. With this PCF, we demonstrated a large-capacity transmission potential of up to 10 times that of current optical fiber, and our paper reporting this result was selected as a post deadline paper at a leading international conference. Going forward, we plan to research means of expanding the range of wavelengths applicable to long-distance transmission and to merge the aforementioned multi-core optical fiber technology with this PCF technology with the aim of achieving the ultimate in large-capacity optical fiber transmission.
--Improving transmission capacity appears to be the dominant theme in your research of optical fiber technologies, but are you researching anything else?
Yes, another direction of our optical fiber research is the creation of new value.
Optical fiber research up to now has been progressing in line with developments in optical transmission systems and requirements.
Of course, optical fiber research will continue moving in this direction, but there is no need to restrict the purpose of using optical fiber to simply the transmission of optical information from one point to another.
For example, if the speed of signals propagating within optical fiber could be freely controlled within the optical fiber network, it might be possible to use the information on the optical signals arriving earlier to simplify the processing of optical signals arriving later. We can also consider the possibility of reducing power consumption throughout the optical transmission system based on innovative optical fiber technology. Similarly, if we could develop optical fiber that can efficiently transmit optical energy itself, we could envision a dramatic expansion of the ways in which optical communications technology might be used. We have already demonstrated the possibility of transmitting high-power laser light having more than 10,000 times the power of optical communications by applying the PCF technology that I discussed earlier. This achievement is attracting attention as a research result that may revolutionize existing ideas about manufacturing by laser processing.
In this way, by taking the initiative and proactively controlling physical quantities such as time and intensity within optical fiber, I think that we may one day be able to integrate diverse social infrastructures under the keyword of "light."
--In what way will the promotion of your research themes change the world and how would you personally like to change the world?
The world that I am aiming for through optical fiber is one that casts off the idea that "physical infrastructure" = "pipes." As I described earlier, optical fiber is not simply a pipeline for optical signals-I believe that it can become a physical infrastructure for integrating a variety of social infrastructures and providing totally new value. At the same time, our prime obligation as researchers of a communications carrier is to continually provide an optical communications infrastructure that can support the ongoing demand for higher transmission capacities. In this regard, let me point out here that an optical communications infrastructure-once deployed-cannot be easily modified or upgraded. For this reason, it is essential in the research and development of an optical communications infrastructure to develop and implement new technologies taking into account their compatibility with existing technologies. To this end, exhibiting leadership in international standardization activities is very important.
I myself have participated in international standards-setting organizations for optical fiber technologies, and since 2009, I have at times served as chairman of such organizations and led discussions on the international standardization of optical-fiber technologies. At present, I believe that the international standardization of optical fiber is entering a transition period in which we must decide on how to move from existing optical fiber standards to the development of innovative technologies such as multi-core optical fiber. Today, in a world in which optical fiber has been deployed just about everywhere, the question "Is optical fiber still being researched?" can be frequently heard. Now, however, is exactly the time to welcome such a transition to new and innovative technologies, so I believe that disseminating information on future optical fiber technologies is once again important.
From here on, I will continue my efforts in the areas of research and development and international standardization with the aim of providing ongoing support for the expansion of the optical fiber network and achieving optical fiber technologies that can interconnect all sorts of people, objects, and things.
PROFILE
Research on optical fiber technology for realizing continuous advances in optical communication infrastructure
Senior Distinguished Researcher
Kazuhide Nakajima
Biography
- 1994
- Joined NTT
- 2011
- Assigned to Distinguished Researcher
- 2018
- Assigned to Senior Distinguished Researcher
Awards
- 2004
- Nikkei BP Technology Award
- 2012
- IEICE Best Paper Award
- 2013
- IEICE Achievement Award
- 2016
- Tsushinbunka Association Maejima Hisoka Award
- 2017
- The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology "Prizes for Science and Technology, Development Category"
