• Title/Summary/Keyword: Optimum Wavelength

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Control and Monitoring of Wavelengths in Spectral Beam Combining System Based on High Resolution Camera (고해상도 카메라 기반 파장 빔 결합 시스템의 다중 광원의 모니터링과 파장 제어 기법 연구)

  • Seung, Ji Hoon;Lee, Kwang Hyun;Lee, Jung Hwan
    • IEMEK Journal of Embedded Systems and Applications
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    • v.14 no.6
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    • pp.321-327
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    • 2019
  • Spectral Beam Combining (SBC) is used for a high-power fiber laser in order to overcome the power limitation of single fiber laser. In SBC, several laser bwams with different wavelengths are combined to obtain a single-aperture beam by diffraction grating. The combining efficiency is dependent on a linewidth, beam quality and specific wavelength of each beam among others. In this paper, we consider the method of a wavelength monitoring and a feedback control of laser diodes used as seeds of laser beams to obtain optimum combining conditions. In order to measure the wavelengths of multi-beam, we use the high resolution camera and diffraction grating with 1,800l/mm. The experiment results show the possibility of feedback control of a current and temperature of multi-seed laser diodes to obtain optimum wavelengths for SBC.

A Cost Analysis of Microalgal Biomass and Biodiesel Production in Open Raceways Treating Municipal Wastewater and under Optimum Light Wavelength

  • Kang, Zion;Kim, Byung-Hyuk;Ramanan, Rishiram;Choi, Jong-Eun;Yang, Ji-Won;Oh, Hee-Mock;Kim, Hee-Sik
    • Journal of Microbiology and Biotechnology
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    • v.25 no.1
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    • pp.109-118
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    • 2015
  • Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

Reduction of Switch Cost by Optimization of Tunable Wavelength Converters and Internal Wavelengths in the Optical Packet Switch with Shared FDL Buffer (공유형 광 지연 선로 버퍼를 갖는 광 패킷 스위치에서 튜닝 가능한 파장 변환기와 내부 파장 개수의 최적화에 의한 스위치 비용 감소)

  • Hwang, Il-Sun;Lim, Huhn-Kuk;Yu, Ki-Sung;Chung, Jin-Wook
    • Journal of Internet Computing and Services
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    • v.7 no.6
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    • pp.113-121
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    • 2006
  • To reduce switch cost, the optimum numbers of tunable wavelength converters (TWCs) and internal wavelengths required for contention resolution of asynchronous and variable length packets like internet traffics, is presented in the optical packet switch (OPS) with the shared fiber delay line (FDL) buffer. To optimize TWCs and internal wavelength related to on OPS design cost, we proposed a scheduling algorithm for the limited TWCs and internal wavelengths. For three TWC alternatives (not shared, partially shared, and fully shared cases), the optimum numbers of TWCs and internal wavelengths to guarantee minimum pocket loss are evaluated to prevent resource waste. Under o given load, TWCs and internal wavelengths could be significantly reduced, guaranteeing the same pocket loss probability as the performance of on OPS with full TWCs and internal wavelengths.

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Characteristic ependences of High Power Semiconductor Laser on AR Coating (AR Coating에 따른 고출력 반도체 레이저의 특성변화)

  • 오윤경;곽계달
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.11
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    • pp.29-34
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    • 1995
  • Mirror coating is applied to laser facets to improve properties of edge emitting laser diodes. In this experiment, InGaAsP/GaAs high power laser diodes were studied with respect to different degrees of anti-reflective coating. Sputterred $Al_{2}$O$_{3}$ was used as the coating material and the HR coating was kept constant at 90%. Threshold current density, differential quantum efficiency, emission wavelength and the operating current at 500mW were measured for a range of AR coating and compared with theoretically calculated values; that showed good agreements. Precise wavelength control is important for laser diodes for solid state pumping because of small absorption bandwidth. In addition, since these lasers operate under CW condition, a lowest possible operating current for a given power is desired in order to minimize the heat produced. From the results of this experiment, we were able to obtain a optimum range of AR coatings for minimum operating current. The wavelength can be varied up to 4nm within this range.

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Optimum design of InGaAsP electroabsorption optical modulator (InGaAsP 전계흡수 광변조기 최적설계에 관한 연구)

  • Han, Sub;Han, Sang-Kook
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.11
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    • pp.83-89
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    • 1997
  • An optimize delectroabsorption modulator structure is designed for high speed optical communication systems considering the extinction efficiency, operating bandwidth, polarization loss, and wavelength chirping. the operating wavelength region is $1.55\mu\textrm{m}$ and the deep ridge structure is adapted for th eminimum polarization loss. Simulations show that the absorption layer thickness larger than $0.25\mu\textrm{m}$, and the modulator length shorter than $200\mu\textrm{m}$ are required for the bandwidth over 10GHz. To obtain the modulatiron efficiency over 10dB/V, a wavelength detuning needs to be determined less than 40meV.

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Performances of Erbium-Doped Fiber Amplifier Using 1530nm-Band Pump for Long Wavelength Multichannel Amplification

  • Choi, Bo-Hun;Chu, Moo-Jung;Park, Hyo-Hoon;Lee, Jong-Hyun
    • ETRI Journal
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    • v.23 no.1
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    • pp.1-8
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    • 2001
  • The performance of a long wavelength-band erbium-doped fiber amplifier (L-band EDFA) using 1530nm-band pumping has been studied. A 1530nm-band pump source is built using a tunable light source and two C-band EDFAs in cascaded configuration, which is able to deliver a maximum output power of 23dBm. Gain coefficient and noise figure (NF) of the L-band EDFA are measured for pump wavelengths between 1530nm and 1560nm. The gain coefficient with a 1545nm pump is more than twice as large as with a 1480nm pump. It indicates that the L-band EDFA consumes low power. The noise figure of 1530nm pump is 6.36dB at worst, which is 0.75dB higher than that of 1480nm pumped EDFA. The optimum pump wavelength range to obtain high gain and low NF in the 1530nm band appears to be between 1530nm and 1540nm. Gain spectra as a function of a pump wavelength have bandwidth of more than 10nm so that a broadband pump source can be used as 1530nm-band pump. The L-band EDFA is also tested for WDM signals. Flat Gain bandwidth is 32nm from 1571.5 to 1603.5nm within 1dB excursion at input signal of -10dBm/ch. These results demonstrate that 1530nm-band pump can be used as a new efficient pump source for L-band EDFAs.

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Characteristics of erbium-doped fiber sources with double-pass forward configuration for gyroscope application (Double-pass forward 방식으로 구성된 자이로스코프용 Erbium 첨가 광섬유 광원의 특성)

  • 진영준;허영순;김택중;박희갑
    • Korean Journal of Optics and Photonics
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    • v.14 no.4
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    • pp.460-465
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    • 2003
  • Characteristics of 0.98 $\mu$m-pumped erbium-doped fiber (EDF) sources with double-pass forward (DPF) configuration are analyzed by numerical calculation. Various source characteristics such as output power, spectral width and mean-wavelength stability are investigated with the variation of EDF length, pump power and pump wavelength. Some of the numerical results are compared with experimental ones for verification. The results show that the characteristics of sources with DPF configuration can change considerably with the EDF length. It is also found that an optimum design can exist for stable mean-wavelength against fluctuations of pump power and pump wavelength.

Development of the Algorithm for Optimizing Wavelength Selection in Multiple Linear Regression

  • Hoeil Chung
    • Near Infrared Analysis
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    • v.1 no.1
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    • pp.1-7
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    • 2000
  • A convenient algorithm for optimizing wavelength selection in multiple linear regression (MLR) has been developed. MOP (MLP Optimization Program) has been developed to test all possible MLR calibration models in a given spectral range and finally find an optimal MLR model with external validation capability. MOP generates all calibration models from all possible combinations of wavelength, and simultaneously calculates SEC (Standard Error of Calibration) and SEV (Standard Error of Validation) by predicting samples in a validation data set. Finally, with determined SEC and SEV, it calculates another parameter called SAD (Sum of SEC, SEV, and Absolute Difference between SEC and SEV: sum(SEC+SEV+Abs(SEC-SEV)). SAD is an useful parameter to find an optimal calibration model without over-fitting by simultaneously evaluating SEC, SEV, and difference of error between calibration and validation. The calibration model corresponding to the smallest SAD value is chosen as an optimum because the errors in both calibration and validation are minimal as well as similar in scale. To evaluate the capability of MOP, the determination of benzene content in unleaded gasoline has been examined. MOP successfully found the optimal calibration model and showed the better calibration and independent prediction performance compared to conventional MLR calibration.

Dynamic characteristics of TbFeCo Magneto-Optical recording media at 680nm wavelength region (680nm 파장에서 TbFeCo 광자기 기록매체의 동특성)

  • Yoon, Doo-Won;Yeon, Cheong;Kim, Myong-Ryeong
    • Electrical & Electronic Materials
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    • v.8 no.5
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    • pp.558-563
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    • 1995
  • Dynamic characteristics of TbFeCo magneto-optical recording media at 680nm wavelength region were studied by means of computer simulation of disc structure and optimization of process variables during sputter deposition. With the slightly reduced Kerr rotation angle due to the reduced wavelength of optical laser source, the improved recording density in TbFeCo magneto optical media showing the CNR greater than 50dB could be achieved by only adjusting the thickness of dielectric and the recording layers when the wavelength of light source is changed from 780nm to 680nm. In addition, the recording power margin of 5mW and the 2mW minimum recording power was realized, It was shown from the present study that the increase in laser power density demonstrated feasibility of low cost and low power laser diode with the reduced optimum recording power.

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