• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.210-215
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• 1995

Technology development toward the use of LiNbO3-based acoustic tunable filters as WDM 2$\times$2 cross-connect switches is reviewed. Recenly, it was found that a fundamental behavior of multi-wavelength Bragg scattering critically affects the crosstalk performance of the acousto-optic tunable filter. We revuew serveral reported methods of overcoming the performance degradation. We will eventually ask whether the device is up to task of WDM optical switching.

• Analytical Science and Technology
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• v.8 no.4
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• pp.1101-1108
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• 1995

Acousto-optic tunable filter is a compact, all solid state electronic dispersive device. It is based on the acousto-optic interaction in an anisotropic crystal. Compared to conventional grating monochromators. the AOTF has no moving parts, wider spectral tuning range (from UV through visible and near-IR to IR), higher throughput, higher resolution, faster scanning (${\mu}s$) and random wavelength access. These features make it possible to use the filter to develop novel instruments which are not possible otherwise. The instrument development and unique advantages of such AOTF based instruments including the multidimensional fluorimeter, the multiwavelength thermal lens spectrometer, and the detectors for HPLC and flow injection analysis are described.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.76-82
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• 1997

The characteristics of optical waeguides and IDT electrodes fabricated for acousto-optic tunable filters (AOTE) used for optical communications were analyzed. A $Ti:LiNbO_3$ in-diffusion method was employed for the formation of the optical waveguide with a dimension of width $8\mu\textrm{m}$, length $30000\mu\textrm{m}$, and thickness $1150{\AA}$. The diffusion was carried at $1050^{\circ}C$ for 8 houss to pattern the optical waveguide with Ti. The resulted waveguide exhibited a single mode at a 1550nm wavelength range and its propagation loss was less than 0.5dB/cm. The width of IDT, with 10 SAW periods, was $5000\mu\textrm{m}$, S11 reflection characteristics and impedances of th eelectrodes deposited with Au were analyzed using a network analyzer; $48.1\Omega$ at th ecenter frquency of 193MHz for Au deposition thickness of $1500{\AA}$ and $50.7\Omega$ at the center frequency of 192MHz for au deposition thickness of $1600{\AA}$.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.152-153
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• 2001

파장 가변형 광 필터와 파장 선택형 광 스위치는 파장분할다중 광통신 및 광 교환 시스템을 구현하는데 매우 중요한 소자들 중의 하나이다. 특히 음향광학효과를 이용한 파장 가변형 광 필터(AOTF ： Acousto-Optic Tunable Filter)는 150nm 이상의 넓은 파장 가변범위, 1.5nm이하의 좁은 통과대역폭, 수 $\mu\textrm{s}$ 정도의 비교적 빠른 스위칭 속도 그리고 여러 개의 파장 채널을 동시에 선택할 수 있는 장점들을 가지고 있지만, 한편으로 표면 음향파(SAW： Surface Acoustic Wave) 구동에 필요한 RF 파워와 부 모드 (sidelobe)가 비교적 크다는 단점 때문에 실용화에 많은 제약을 받아왔다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.154-155
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• 2001

파장가변 광 필터는 WDM 광전송 시스템에 필요로 하는 핵심 부품중의 하나이다. 특히 LiNbO$_3$의 음향광학효과를 이용하는 AOTF(Acousto-Optic Tunable Filter)는 150nm 이상의 파장 가변 범위, 1.5nm 이하의 파장 통과대역폭, 수 $\mu\textrm{s}$ 정도의 비교적 빠른 스위칭 속도, 그리고 여러 파장 채널을 동시에 선택할 수 있는 장점들을 보유하고 있음에도 불구하고 표면 음향파(SAW： SurFace Acoustic Wave) 구동에 필요한 RF 파워와 부 모드(sidelobe)가 비교적 크다는 단점 때문에 실용화에 많은 제약을 받아왔다. (중략)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.8
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• pp.637-645
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• 1998

The characteristics of waveguide, electrode and packaging fabricated for acousto-optic tunable filters(AOTF) used for optical communications were analyzed. A $Ti:LiNbO_3$in-diffusing method was employed for the formation of the optical waveguide with a dimension of width $8{\mu}m$, length $30000-50000{\mu}m$ and varying the thickness. The diffusion was carried at $1050^{\circ}C$ for 8 hours to pattern the optical waveguide. The resulted waveguide exhibited a single mode at 1550nm optical wavelength. The width of IDT, with 10 SAM periods, was $5000{\mu}m$ . Impedances of the electrodes deposited with Au were analyzed using a network analyzer; $48.1\Omega$ at the center frequency of 193MHz for electrode thickness of $1500{\AA}$ and $50.7\Omega$ at the center frequency of 192MHz for $1600\AA$. And the characteristics of packaged AOTF was analyzed. When the electrical frequency 177.1MHz was applied to the device, the mode conversion efficiency was measured as 63% at the optical wavelength 1515nm.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.248-249
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• 2000

파장분할다중 광통신시스템은 파장통과 대역폭이 좁으면서, 파장통과 대역을 넓게 가변시킬 수 있는 집적광학형 광여파기를 필요로 하고 있다. 지금까지 전기광학효과$^{(1)}$ , 스트레인광학효과$^{(2)}$ , 음향광학효과$^{(3)}$ 들을 이용하여 다양한 형태의 광여파기들이 연구되어져왔다. 특히 음향광학효과를 이용한 편광모드변환형 가변파장 광필터 (AOTF: Acousto-Optic Tunable Filter)는 150nm 이상의 넓은 파장가변 범위, 1nm이하의 좁은 파장대역폭, 수 $\mu\textrm{s}$ 정도의 비교적 빠른 스위칭 속도, 그리고 여러 파장 채널을 동시에 선택할 수 있는 특성들 때문에 많은 연구가 진행되어져 왔다. 본 논문에서는 음향파 장벽(acoustic barrier)를 이용하여 표면 음향파(SAW: Surface Acoustic Wave)의 RF 구동파워를 감소시킬 수 있는 구조의 AOTF를 제작하고, 측정 결과를 음향파 장벽을 이용하지 않은 AOTF의 측정 결과와 비교, 검토하였다. (중략)

• Korean Journal of Materials Research
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• v.28 no.12
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• pp.732-737
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• 2018

We develop a purification process of $Hg_2Br_2$ raw powders using a physical vapor transport(PVT) process, which is essential for the fabrication of a high performance acousto-optic tunable filter(AOTF) module. Specifically, we characterize and compare three $Hg_2Br_2$ powders: $Hg_2Br_2$ raw powder, $Hg_2Br_2$ powder purified under pumping conditions, and $Hg_2Br_2$ powder purified under vacuum sealing. Before and after purification, we characterize the powder samples through X-ray diffraction and X-ray photoelectron spectroscopy. The corresponding results indicate that physical properties of the $Hg_2Br_2$ compound are not damaged even after the purification process. The impurities and concentration in the purified $Hg_2Br_2$ powder are evaluated by inductively coupled plasma-mass spectroscopy. Notably, compared to the sample purified under pumping conditions, the purification process under vacuum sealing results in a higher purity $Hg_2Br_2$ (99.999 %). In addition, when the second vacuum sealing purification process is performed, the remaining impurities are almost removed, giving rise to $Hg_2Br_2$ with ultra-high purity. This high purification process might be possible due to independent control of impurities and $Hg_2Br_2$ materials under the optimized vacuum sealing. Preparation of such a highly purified $Hg_2Br_2$ materials will pave a promising way toward a high-quality $Hg_2Br_2$ single crystal and then high performance AOTF modules.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.193-197
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• 2000

A polarized mode convertible, wavelength tunable optical filters with acoustic barriers and acousto-optic effect have been produced in LiNb03 substrate utilizing the Ti double diffusion technique. Polarization conversion in excess of 81 % and a spectral width of -200 kHz (-1.83 nm) were achieved at a wavelength of 1551.6 nm and RF frequencies of 173.07 kHz and 173.05 kHz for both transverse electric (TE) and transverse magnetic (lM) input polarizations, respectively. The electrical driving power was 10.97 mW and reduced to about 10% of one for an optical filter without an acoustic barrier. A linear tuning rate of 8.2 nmlMHz and sidelobe intensity of -4 dB was demonstrated. rated.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.72-73
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• 2000

Optical fiber gratings have been intensively studied for applications in optical fiber communications and sensor systems due to their all-fiber configuration, low insertion loss, low cost, and high flexibility. Especially, cladding mode coupling fiber devices such as long period gratings (LPG) and acousto-optic tunable filters (AOTF) have been developed as a gain equalization filter in erbium doped fiber amplifier (EDFA) for wavelength division multiplexing (WDM) systems$^{(1-2)}$ . (omitted)