Toshiyuki Ando

Compact all-fiber pulsed coherent Doppler lidar system for wind sensing

A compact 1.5 microm all-fiber pulsed coherent Doppler lidar system for wind sensing, which includes the functions of variable pulse width and automatic polarization control has been developed. The system configuration is introduced and key components used in the system are explained. Theoretical performances of the system in wind sensing are estimated and compared with experimental results. The measurable range corresponding to the detection probability of >80% is approximately 1 km or more in the case of 150 m range resolution under the normal atmospheric conditions.

Development of an Onboard Doppler Lidar for Flight Safety

Air turbulence has become a major cause of significant injuries and aircraft damages. Timely advanced warning of turbulence ahead of an aircraft may allow pilots to take appropriate action to minimize potential damage, such as reducing speed and securing passengers and unsecured objects, or to avoid the turbulence altogether. The aim of our research is to develop a practical, onboard, Lidar-based proactive sensor that will detect air turbulence in clear air at a range of 5 n miles (9.3 km) at cruising altitudes. In February 2007 we successfully measured wind speeds approximately 3 n miles (5.6 km) ahead of an aircraft in low-altitude flight experiments, and in a subsequent experiment in July of the same year, we succeeded in detecting air turbulence before encountering it. An upgraded 5-n-mile Lidar for low altitudes was developed in fiscal year 2007, and has successfully measured wind speeds at ranges up to 5 n miles in ground tests. This paper describes the master development plan of our Lidar turbulence sensor and the results of basic flight and ground experiments.

Coherent homodyne receiver with a compensator of Doppler shifts for inter orbit optical communication

This paper presents Bread Board Model (BBM) of coherent homodyne receiver with an optical phase locked loop and a frequency compensator of Doppler shifts for inter satellite optical communication link. 2.5Gbps BPSK data has been demodulated with sensitivity of -49.1dBm at bit rate of 1e-6 under initial frequency offset of +/-7 GHz simulated as Doppler shifts due to variation of distance between each satellite.

Phase stabilized RF reference signal dissemination over optical fiber employing instantaneous frequency control by VCO

Stable microwave reference signal transfer systems are required in communication systems, very long baseline interferometer (VLBI) radio astronomy applications, particle accelerators and metrologies. Radio over fiber (RoF) technique is one of candidates which realize precise microwave dissemination without degradation of stability. We developed the precision microwave signal dissemination system in which a fluctuation of phase caused by transmitting optical fiber thermal expansion. This system monitors a phase of the signal reflected at destination, and controls transmitting signal frequency using a voltage controlled oscillator (VCO). The measurement shows that the phase error is 0.098 deg (r.m.s) of the 1.0 GHz microwave signal in 1-km length single mode fiber over 10 hours.

Homodyne BPSK receiver with Doppler shift compensation for inter satellite optical communication

This paper presents Bread Board Model (BBM) of homodyne BPSK (Binary Phase Shift Keying) receiver with an optical phase locked loop and a Doppler shifts compensator for inter satellite optical communication link. 2.5Gbps BPSK data has been demodulated with sensitivity of −49.1dBm at bit error rate of 1e-6 under initial frequency offset of +/−7.5 GHz simulated as Doppler shifts due to relative motion of each satellite.

All-fiber coherent Doppler LIDAR technologies at Mitsubishi Electric Corporation

A 1.5 micron pulsed Coherent Doppler LIDAR system using all fiber optical components has been attracted attention for remote wind sensing because of its eye-safety, reliability and easy deployment. We report on our key technologies such as fiber based MOPA (Master Oscillator Power Amplification) transmitter and real-time signal processing. Some performance results are also provided.

Spatial light modulator based optically controlled beamformer for variable multiple-spot beam antenna

We propose and demonstrate an optically controlled multiple-beam phased array antenna employing spatial light modulator. Developed prototype of the optical beamformer enables control multiple-beam direction and width; we demonstrated beamforming operation at 18 GHz. Furthermore, we have performed the communication test such as the bit error ratio (BER) test, data rate of 622 Mbps and 1244 Mbps in the digital communication link. We have confirmed that this optical beamformer had no serious effect for BER performance.

All Fiber Coherent Doppler LIDAR for Wind Sensing

An 1.5 micron pulsed Coherent Doppler LIDAR system using all fiber optical components has attracted attention for remote wind sensing application because of its eye-safety, reliability and easy deployment. We report on our key technologies such as fiber based MOPA (Master Oscillator Power Amplification) transmitter, high peak power optical amplification and a real-time signal processing. Some performance results and applications are also provided.

Development of an airborne wind measurement system

Accidents to airliners caused by air turbulence have been increasing in recent years. At present there is no sure way of avoiding encounters with clear air turbulence (CAT) because conventional airborne weather radars cannot detect turbulence in clear conditions. The Japan Aerospace Exploration Agency (JAXA) is therefore developing a Doppler LIDAR (Light Detection and Ranging) which can measure wind speeds ahead of an aircraft even in clear air. Turbulence prediction in flight has already been demonstrated using experimental Doppler LIDARs, and the latest prototype aims at turbulence detection up to 5 nautical miles (9 km) ahead at jet airliner cruising altitudes. Wind velocity measurement by LIDAR is difficult at high altitude because of low aerosol particle density. Regular atmospheric observation flights are therefore being made to establish the basic specifications of a practical device. Furthermore, since air turbulence information should be displayed on the flight deck, a graphical turbulence display is also being studied. This paper describes the development of the airborne wind measurement system and presents examples of flight experiment results.

Optical coherent beam control based on microwave photonics technologies

Optical coherent beam control is attractive technique to realize precise and high-speed control of a far field beam pattern, to increase optical power with high beam brightness, and to ensure robustness on optical communication link between satellites. In the above applications optical phase and intensity of single or multiple beams have to be precisely detected and distinguished. Microwave photonics perform important roles for extraction of this optical information. We describe coherent beam combining technology of multiple phase modulated beams and optical coherent receiver technology for inter-satellite communication as our recent activities.