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Mitsubishi Electric Develops World’s First Laser Communication Terminal
Integrating Space Optical Communication and Spatial Acquisition
Will enable high-speed, large-capacity satellite communications anywhere on Earth

Optical receiver prototype forlaser communication terminal (LCT)

Concept of free-space optical communications network
connecting everywhereTOKYO, May 31, 2022 – Mitsubishi Electric Corporation (TOKYO: 6503) announced today that it hasdeveloped the prototype of what is believed to be the world’s first* optical receiver for use in laser
communication terminals (LCTs), that integrates space optical communication using laser beams and afunction to detect the direction of received beams in the 1.5-μm band, a general-purposeband used for
terrestrial optical fiber communications and other applications.
High-resolution satellite imagery is used to assess damage caused by disasters, but since such images aretransmitted via radio waves it has been difficult to transmit high-resolution images in real time due tolimitations in data capacity and the size of satellite antennas. Large-capacity, high-speed space opticalcommunications that do not require optical fiber are thus required to support fast and accurate damage
assessments following disasters. But space optical communications use very narrow laser beams, about
1/1000th of that of radio waves, so the challenge has been how to precisely align laser beams with satellites
traveling at high speed.
Mitsubishi Electric has now developed an optical receiver that solves this problem by integrating functions todetect both four phase changes of laser light and beam direction. The result is a downsized optical receiverthat enables space optical communication with 10 times the speed, capacity and distance of radio-wavecommunication. Since the wavelength is much shorter, smaller antennas can be used in compact* According to Mitsubishi Electric’s research as of May 31, 2022

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communication units that can be installed in locations difficult for optical fiber, such as between buildings.
Installations also are possible in areas where normal infrastructure is not available, such as disaster zones,
developing countries or remote areas, thereby expanding the use of wireless communications in a variety ofsituations.
Features1)

World’s first optical receiver that integrates spatial laser acquisition in the photodetector- The photoelectric converter, which receives laser light and converts it into electrical signals, is divided
into four segments and the direction of received laser beams is detected with high precision bycomparing the output signal intensity of each segmented element. The dedicated sensor for detecting
beam directions in conventional systems is no longer necessary.
- The small optical receiver integrates functions for space optical communication and laser angle-ofarrival detection in a photodetector, which is believed to be a world’s first.
Lens

Quadrant
photodetector

10 mmyθReceived laser beam

Quadrant
photodetectorx

New quadrant photodetector

Direction of arriving laser beam direction (q)measured from the beam’s focal point (x, y)

2)

Optical circuit detects four phase changes for high-speed, large-capacity communications- A newly developed optical circuit for coherent space optical communication detects four phase changes(0, 90, 180, and 270 degrees) in contrast to conventional two-phase (0 and 180 degrees) detection. As
a result, communication capacity and speed are double those of two-phase optical communication
schemes in the same bandwidth and some 10 times those of radio-wave communication systems.
- The coherent detection method enables communication even with weaker laser beams compared to theconventional method of detecting intensity changes due to beams turning on and off, thus enabling
communication over longer distances using the same laser-beam intensity. In addition, the coherent
method is less influenced by sunlight and other background light for more stable communications.
Received laser beam
Phase reference laser beam
Phase changes
90 deg.
270 deg.
0 deg.
180 deg.
New optical circuit

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Optical receiver integrates photodetectors and optical circuit in one small (10 cm3), lightweight module- The photodetectors’ beam-direction detection function eliminates the need for a dedicated sensor.
Furthermore, the optical circuit is contained on a small 5cm-by-5cm glass substrate, mounting two
photodetectors on a single printed circuit board. The single-module configuration realizes a lightweight
optical receiver measuring just 10 cm3, less than one-fourth the size of Mitsubishi Electric’s previousmodel.
Quadrature photodetector

Photodetector (1)Optical circuit
Photodetector (3)Optical circuit

Received
laser beam

Photodetector (2)Photodetector (4)Received
laser beamPrevious optical receiver

New optical receiver

Future Plans and Prospects
Development targeting on-board use in satellites will proceed, mainly for government-sponsored development
programs.
###About Mitsubishi Electric Corporation
With more than 100 years of experience in providing reliable, high-quality products, Mitsubishi ElectricCorporation (TOKYO: 6503) is a recognized world leader in the manufacture, marketing and sales of electricaland electronic equipment used in information processing and communications, space development and satellite
communications, consumer electronics, industrial technology, energy, transportation and building equipment.
Mitsubishi Electric enriches society with technology in the spirit of its “Changes for the Better.” The companyrecorded a revenue of 4,476.7 billion yen (U.S.$ 36.7 billion*) in the fiscal year ended March 31, 2022. For
more information, please visit www.MitsubishiElectric.com*U.S. dollar amounts are translated from yen at the rate of ¥122=U.S.$1, the approximate rate on the Tokyo
Foreign Exchange Market on March 31, 2022

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