• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.334-335
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• 2020

본 논문에서는 레이저 광원을 적용한 무선전력전송 시스템에 적용되는 PV 모듈의 출력 특성을 분석하고, PV 모듈로부터 최대 전력을 발생시키면서 배터리를 충전시킬 수 있는 컨버터 개발 결과를 제시한다. 먼저, 특정 파장에서 최대전력이 발생되도록 개발된 PV 수신모듈에 레이저 빔을 조사하였고, 레이저에 공급되는 전력 크기에 따른 PV 모듈의 전압-전류의 특성 데이터를 확보하였다. 전압/전류 특성 데이터로부터 PV 수신모듈의 소신호 저항을 분석하였고, 이를 컨버터 회로모델에 적용함으로써 제어기 설계를 위한 시스템의 전달함수를 유도하였다. 이로부터 레이저 일사량에 따른 전류원/전압원 전영역에서 PV 모듈의 입력전압을 안정적으로 제어할 수 있는 제어기를 설계함으로써 레이저 수신용 PV 모듈이 최대 전력을 발생시킬 수 있도록 하였다. 본 논문에서 제안된 방법은 MCU 제어기반 25W급 배터리 충전용 부스트 컨버터의 프로토타입 제품을 통해 실험 검증되었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.853-858
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• 2022

In this paper, we show a simultaneous transmission of underwater optical wireless power transfer and underwater optical wireless communication. A laser diode is used for electric-to-optic conversion at the transmitter and a solar cell is used for optic-to-electric conversion at the receiver. We optimized the transmitter and receiver for the best performance. The laser diode is a 100-mW laser diode and showed a conversion efficiency of 18.5%. The experimental results showed a 0.33-% DC-to-DC underwater power transfer efficiency at 5 m and a data rate of 100 kbps at 1 m.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.150-156
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• 2024

One of the key factors in research regarding long-distance laser beam propagation, as in free-space optical communication or laser power transmission, is the transmission efficiency of the laser beam. As a way to improve efficiency, we perform extensive numerical simulations of the effect of modifying the laser beam's profile, especially replacing the fundamental Gaussian beam with a super-Gaussian beam. Numerical simulations of the transmitted power in the ideal diffraction-limited beam diameter determined by the optical system of the transmitter, after about 1-km propagation, reveal that the second-order super-Gaussian beam can yield superior performance to that of the fundamental Gaussian beam, in both single-channel and coherently combined multi-channel laser transmitters. The improvement of the transmission efficiency for a 1-km propagation distance when using a second-order super-Gaussian beam, in comparison with a fundamental Gaussian beam, is estimated at over 1.2% in the singlechannel laser transmitter, and over 4.2% and over 4.6% in coherently combined 3- and 7-channel laser transmitters, respectively. For a range of the propagation distance varying from 750 to 1,250 m, the improvement in transmission efficiency by use of the second-order super-Gaussian beam is estimated at over 1.2% in the single-channel laser transmitter, and over 4.1% and over 4.0% in the coherently combined 3- and 7-channel laser transmitters, respectively. These simulation results will pave the way for future advances in the generation of higher-order super-Gaussian beams and the development of long-distance optical energy-transfer technology.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.12
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• pp.1219-1224
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• 2016

The current wireless power charge technologies are based on induction coupling, magnetic resonant coupling, electromagnetic wave, etc. However, the current wireless power charge technologies has several disadvantages including short transfer range, electromagnetic interference, etc. In this paper, we investigate and demonstrate a laser wireless power charge technology. A laser source is used in the transmitter to convert from electric power to optical power and a solar cell or a photodiode is used in the receiver to convert from optical power to electric power. The laser wireless power charge technology may be the most efficient wireless power charge technology in the long distance over than 10 meters. Our experimental results show a transfer efficiency of 2.15% at the 70-m long distance with a 100 mW laser transmitter and a photodiode receiver.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.605-610
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• 2021

Wireless charging method using a laser is considered as the most efficient method at a long distance of the wireless charging method. Combining long-range laser wireless charging technology with wireless communication technology will make it possible to use it for a variety of applications. Accordingly, this paper shows the results of research and experiments on wireless charging and wireless communication simultaneously based on a laser. This technique uses a laser as a light source for E/O(: Electric-to-Optical) conversion at the transmitter for optical wireless power transmission. In the experimental results, the optical power transmission using a 100 mW laser transmitter and a solar cells receiver showed a DC-to-DC efficiency of 1.9 %, wireless optical communication showed a transmission speed of up to 90 kbps when the transmission distance is 15 m.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.265-270
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• 2000

We investigate the effects of the power and wavelength of externally injection seeded light on timing jitter and pulse width in a gain-switched $1.55\mu\textrm{m}$ DFB semiconductor laser by numerical simulation based on the transmission line laser model. As external seeding power increases, the timing jitter decreases and the pulse width increases. The lowest timing jitter is observed when the seed wavelength is aligned with the chirped spectrum center. By external seeding, we can decrease the timing jitter up to 1/2.7 without noticeable increase in pulse width. Our simulation results reasonably well agree with our sampled experiment and the other published papers. This proves the validity of our model to analyze a system based on a semiconductor laser. laser.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.18-29
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• 1993

In single mode fiber optic transmission systems(FOT's) operated at high modulation rates over long fiber spans, chromatic dispersion can produce distortion in the demodulated waveforms, resulting in intersymbol interference(ISI) in the received signal and a reduction of transmission system performance. In this paper, chromatic dispersion limitations for intensity modulation and direct detection(IM-DD) systems are studied by considering the effect of phase modulation to amplitude modulation (PM-AM) conversion noise. Laser phase noise conversion to amplitude noise due to fiber chromatic dispersion is analyzed by deriving the noise power spectral density. We first derive the noise power spectral density of the laser phase noise to intensity noise conver- sion. Next, also evaluate the system power penalty and the transmitter laser linewidth required to avoid PM-AM conversion noise penalties in long-haul nonregenerative transmission system using an external modulator and optical amplifiers. For such system with optical amplifiers, transmission sys- tem length is limited due to fiber chromatic dispersion, even if an ideal external modulator is used.

• Journal of Space Technology and Applications
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• v.4 no.2
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• pp.87-104
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• 2024

CubeSats are being utilized in various fields such as Earth observation, space exploration, and verification of space science and technology due to their low cost, short development period, enhanced mission-oriented performance, and ability to perform various missions through constellation and formation flights. Recently, as the availability of CubeSats has increased and their application areas have expanded, the demand for high-speed transmission of large amounts of data obtained by CubeSats has increased unprecedentedly. Laser-based free space optical communication technology is capable of transmitting large amounts of data at high speeds compared to the existing radio communication methods, and provides various advantages such as use of unlicensed spectrum, low cost, low power, high security characteristics, and of use a small communication platform. For this reason, it is suitable as a high-performance communication technology to support CubeSat missions. In this paper, we will present the core components and characteristics of CubeSat-based space laser communication system, and recent research trends, as well as representative technology development results.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.194-199
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• 1998

In the atmospheric wireless optical communication system, the low power transmission can be accomplished by the high directivity of laser beam. But, the transmitted optical signal undergoes the serious influences by the atmospheric effects like absorption, scattering, and turbulence because the transmission channel is the atmospheric space. In this paper, therefore, we obtain the link equation for an atmospheric wireless optical LOS communication link under the atmospheric effects and find the repeaterless transmission length to estimate the system performance through the computer simulation. From the results of the computer simulation, we present the transmission length that is possible to transmit without a repeater at given data rates and know that data rate is decreased rapidly when the transmission length is increased slightly at given bit error rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.237-242
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• 1999

In this paper, we analyze transmission characteristics of ultrashort laser pulses using the property of high-order pulses which are systematically obtained following their orders. The high-order pulses are easily derived from a modified PRS system model. But we make clear they are very useful to cover wider area and more accurate transmission characteristics of ultrashort pulses than Gaussian or Sech pulse approximations used conventionally. This may be based on the fact that the spectra and bandwidths of the high-order pulses are beautifully related to their orders. first modifying the generalized PRS system model, we propose a new model for deriving any type of high-order pulse. And we offer a novel analysis method of ultrashort pulse transmission which has any shape and FWHM, using the proposed model. In addition, by fixing the pulse range $\tau$=1(ps) and varying the order of the pulse from n:1 to n=100, we obtain spectra of ultrashort pulses with 1(ps)-150(fs) FWHM's, which are widely used in fiber communications. As a one-step further, we derive PSD's of their pulse trains when they are applied to Unipolar signaling scheme. These PSD's are decided in the range of possible pulse intervals. All of these results are not only coincided with some conventional experimental works but also will be applied to any pioneering ultrashort pulse in the future.