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Implementation of the Optical Filter Using FBG (FBG를 이용한 Optical Finer 구현)

  • 이종윤;신희성;손용환;이창원;정진호
    • Proceedings of the IEEK Conference
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    • 2002.06a
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    • pp.223-226
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    • 2002
  • In this paper, we propose the FBG design using coupled mode theory based on perturbation theory. FBG can be used to extract the specific wavelength channel from the transmission ]me when many wavelengths are coupled in a multiwavelength transmission line. To analyze output characteristics of FBG and get optimum design data, we simulate through computer and verify by experiment. From the results obtained by simulation and experimentation, the proposed FBG fits for DWDM(Dense WBM) system because of the tunning narrow linewidth.

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Optical Properties of Admolecules near a Phase -Conjugate Mirror (위상 공액 거울에 흡착된 분자의 광학적 성질)

  • 김영식
    • Journal of the Korean Vacuum Society
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    • v.5 no.1
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    • pp.33-38
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    • 1996
  • The induced linewidth, frequency shift and absorption spectrum for a molecular dipole in the vicinity of a phase -conjugate mirror have been investgated within a classical phenomenological model, with particularreference to the technique of optical phase conjugation by a surface. While the shifts and the widths show similar characteristics as those obtained recently by Bochove who considered the problem within the context of four-wave mixing, the results obtained in the present model can be defined uniquely with the possibility of an infinite lifetime for the excited admolecule . Furthermore, the absorption lineshape obtained here some interesting features which depend on both the magnitude and the phase of the complex reflectivity of the mirror.

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Construction and characterization of broadband erbium-doped fiber sources for gyroscope (Gyroscope용 광대역폭 Erbium 첨가 광섬유 광원의 구성과 특성 측정)

  • 임경아;진영준;박희갑
    • Korean Journal of Optics and Photonics
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    • v.8 no.4
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    • pp.320-326
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    • 1997
  • Broadband sources for fiber-optic gyroscope were constructed using erbium-doped fibers. Output power, linewidth, and mean wavelength were compared between four different source configurations. Among them, double pass configuration exhibited the highest output power, as high as 5.5 mW with 25 mW pumping at 1.48 ${\mu}{\textrm}{m}$ wavelength. It also showed nearly zero sensitivity of mean wavelength for the variation of pump power when a sufficient pumping was provided. Amplifier/Source configuration resulted in the highest detected power(power received by the gyro detector) that is more than 100 times larger than those of the other configurations, though it was the lowest of source output power. As the feedback level increased, the source power decreased while the linewidth increased, and mean wavelength varied significantly which would affect the scale factor of the gyroscope.

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A Study on the Effect of Reducing the Saturation Magnetization by Substituting the Non magnetic Ion in Mg Mn Ferrites (Mg-Mn훼라이트의 비자성 이온첨가에 의한 포화자화 감소효과)

  • Yu, Byeong-Du;Kim, Jong-O
    • Korean Journal of Materials Research
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    • v.4 no.1
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    • pp.117-124
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    • 1994
  • The reduction of saturation magnetization in the Mg-Mn microwave ferrites was achieved by substituting the non-magnetic A1 ion for Fe ion. It is necessary for extending the operation frequencies that there is no change in other properties of the microwave ferrites. The electrical and magnetic properties are characterized where the composition of the ferrites studied was given by the general formula $(MgO)_{1.0}(MnO)_{0.1}(Al_xFe_{1.9-x}O_{2.85}$ with x ranging from 0.1 to 0.4. The saturation magnetization and the ferromagnetic resonance linewidth was decreased by the substituting amount of $Al_2O_3$. The value of coercive field was low enough over the composition of x=O.2 and the high squareness ratio was obtained all over the amount of substitution. It is feasible to select the proper application area with the combination of various properties ; that is, low coercive field, high squareness ratio, optimum saturation magnetization and ferromagnetic resonance linewidth.

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ESR spectrum change for the a-C : H films exposed in the atmosphere (공기 중에 노출된 a-C : H 박막의 ESR 스펙트럼 변화)

  • 윤원주;이정근
    • Journal of the Korean Vacuum Society
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    • v.13 no.2
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    • pp.65-71
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    • 2004
  • ESR spectrum change has been investigated for the PECVD deposited a-C : H films exposed in the atmosphere. Though depending on the deposition conditions, it was observed that generally ESR signal height decreased and linewidth increased as the exposure time increased. The spin density decreased down to 40-80% depending on samples. The decrease of spin density of the a-C : H films in the air was attributed to permeation of moisture into the films and subsequent migration and redistribution of hydrogens. And the ESR signal height increased again and the linewidth decreased when the a-C : H samples were placed again in the vacuum, which was attributed to oxygens extracted from the samples. Consequently, the ESR spectrum change for the a-C : H films exposed in the air was regarded to be associated with the decrease of spin density as well as the permeation of oxygens into films.

Thermal Annealing Effect on Ferromagnetic Resonance Properties in CoFeB/MgO Thin Film (CoFeB/MgO 박막 재료의 열처리에 따른 강자성공명 특성)

  • Yoon, Seok-Soo;Kim, Dong-Young
    • Journal of the Korean Magnetics Society
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    • v.21 no.1
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    • pp.10-14
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    • 2011
  • We have measured the ferromagnetic resonance (FMR) signal in as deposited and $400^{\circ}C$ annealed CoFeB/MgO thin film to investigate the annealing effect on magnetic anisotropies and FMR linewidth (${\Delta}H_{PP}$). The uniaxial anisotropy field ($H_{K1}$) was only observed in the as deposited sample. Whereas, in the $400^{\circ}C$ annealed sample, the biaxial anisotropy field ($H_{K2}$) was additionally observed in accompany with uniaxial anisotropy field ($H_{K1}$). The appearance of biaxial anisotropy fields was originated from the crystalline growth of bcc CoFeB(001) from the MgO(001) interface and by the B diffusion during thermal annealing. Also, the ${\Delta}H_{PP}$ of $400^{\circ}C$ annealed sample was increased compared with that of as deposited sample, which was due to the broad distribution of the magnetization axis by the biaxial anisotropy.

Optimization of multiple-quantum-well structures in 1.55.$\mu$ InGaAsP/InGaAsP SL-MQW DFB-LD for high-speed direct modulation (고속직접변조를 위한 1.55.$\mu$. InGaAsP/InGaAsP SL-MQW DFB-LD의 양자우물구조의 최적화)

  • 심종인;한백형
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.3
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    • pp.60-73
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    • 1997
  • By introducing a compressive-strained quanternary InGaAsP quantum-wells instead of a conventional ternary InGaAs quantum-wells in 1.55.mu.m DFB-LD, the lasing performances canb e improved and the problems caused by the thickness non-uniformity and the compositional abruptness among the hetero-interpaces canb e relaxed. In this paper, we investigated an iptimum InGaAsP/InGaAsP multiple-quantum-well(MQW) structure as an active layer in a direct-modulated 1.55.mu. DFB-LD from the view point of threshold current, chirping charcteristics, and resonance frequency. The optimum compressive-strained MQW structure was revealed as InGaAsP/InGaAsP structure with strain amount of about 1.2%, number of wells $N_{w}$ of 7, well width $L_{w}$ of 58.agns.. The threshold current density J of 500A/c $m^{2}$, the linewidth enhancement factor a of 1.8, and differential resonance frequency of d $f_{r}$/d(I-I)$^{1}$2/=2GHz/(mA)$^{1}$2/(atI=2 $I_{th}$) were expected in 1.55.mu.m .gamma./4-shifted DFB-LD with the cavity length of 400.mu.m long and kL value of 1.25. These values are considerably improved ones compared to those of 1.55um DFB-LD with InGaAs/InGaAsP MQW which have enhancement factor and the resonance frequence frequency by the detuning of lasing wavelength and gain-peak wavelength. It was found that the linewidth enhancement factor of 20% and differential resonance frequency of 35% without the degradation of the threshold current density could be enhanced in the range of -15nm~-20nm detuning which can be realized by controlling the thickness and Incomposition of InGaAsP well. well.and Incomposition of InGaAsP well. well.

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Development of the Growth and Wavelength Control Technique of In As Quantum Dots for 1.3 μm Optical Communication Devices (1.3 μm 광통신용 소자를 위한 InAs 양자점 성장 및 파장조절기술 개발)

  • Park, Ho-Jin;Kim, Do-Yeob;Kim, Goon-Sik;Kim, Jong-Ho;Ryu, H.H.;Jeon, Min-Hyon;Leem, Jae-Young
    • Korean Journal of Materials Research
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    • v.17 no.7
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    • pp.390-395
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    • 2007
  • We systematically investigated the effects of InAs coverage variation, two-step annealing and an asymmetric InGaAs quantum well (QW) on the structural and optical characteristics of InAs quantum dots (QDs) by using atomic force microscopy (AFM), transmission electron microscopy (TEM) and photoluminescence (PL) measurement. The transition of size distribution of InAs QDs from bimodal to multi-modal was noticeably observed with increasing InAs coverage. By means of two-step annealing, it is found that significant narrowing of the luminescence linewidth (from 132 to 31 meV) from the InAs QDs occurs together with about 150 meV blueshift, compared to as-grown InAs QDs. Finally, the InAs QDs emitting at longer wavelength of $1.3\;{\mu}m$ with narrow linewidth were grown by an asymmetric InGaAs QW. The excited-state transition for the InAs QDs with an asymmetric InGaAs QW was not noticeably observed due to the large energy-level spacing between the ground states and the first excited states. The InAs QDs with an asymmetric InGaAs QW will be promising for the device applications such as $1.3\;{\mu}m$ optical-fiber communication.

Taguchi method-optimized roll nanoimprinted polarizer integration in high-brightness display

  • Lee, Dae-Young;Nam, Jung-Gun;Han, Kang-Soo;Yeo, Yun-Jong;Lee, Useung;Cho, Sang-Hwan;Ok, Jong G.
    • Advances in nano research
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    • v.13 no.2
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    • pp.199-206
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    • 2022
  • We present the high-brightness large-area 10.1" in-cell polarizer display panel integrated with a wire grid polarizer (WGP) and metal reflector, from the initial design to final system development in a commercially feasible level. We have modeled and developed the WGP architecture integrated with the metal reflector in a single in-cell layer, to achieve excellent polarization efficiency as well as brightness enhancement through the light recycling effect. After the optimization of key experimental parameters via Taguchi method, the roll nanoimprint lithography employing a flexible large-area tiled mold has been utilized to create the 90 nm-pitch polymer resist pattern with the 54.1 nm linewidth and 5.1 nm residual layer thickness. The 90 nm-pitch Al gratings with the 51.4 nm linewidth and 2150 Å height have been successfully fabricated after subsequent etch process, providing the in-cell WGPs with high optical performance in the entire visible light regime. Finally we have integrated the WGP in a commercial 10.1" display device and demonstrated its actual operation, exhibiting 1.24 times enhancement of brightness compared to a conventional film polarizer-based one, with the contrast ratio of 1,004:1. Polarization efficiency and transmittance of the developed WGPs in an in-cell polarizer panel achieve 99.995 % and 42.3 %, respectively.

Formation of Submicron Top Pattern by using Tri-Layer Resist Structure (심층 레지스터 구조를 이용한 서브미크론 상층패턴 형성)

  • 심규환;양전욱;이진희;강진영;마동성
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.5
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    • pp.495-500
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    • 1988
  • The effectiveness of tri layer resist (TLR) technique is compared with that of single layer resist (SLR) technique in order to make a 0.8um pattern with the linewidth deviation of 10 percents. SLR technique is not appropriate to shape the micro-pattern on oxide and aluminum steps because of the standing wave effect and the light scattering effect in shaping the resist pattern. On the contrary, the uniform line with a width of 0.8um on oxide and aluminum steps can be formed by TLR technique, reducting such effects. The planarization and the light absorption coefficient of the bottom layer resist in TLR are optimized by exposing it to ultra violet light after baking it for 30min at 230\ulcorner. An uniform line with a width of 0.8um on oxide step is defined with the light absorption coefficient of 0.85 whereas that on aluminum step is defined with 0.95.

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