• Publications of The Korean Astronomical Society
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• v.27 no.3
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• pp.87-93
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• 2012

A low-dispersion fiber feed Littrow-mounted grating spectrometer for education was designed and fabricated. The dispersion element is a reflective type blazed grating Edmundoptics NT 46-075 (spatial frequency 600 lines/mm, dimension $30mm{\times}30mm$, blazed angle 8.6 degree). The optical fiber coupler module for optical guiding from telescope to spectrometer is composed of a multi-mode FC connector - FC connector optical fiber patch cord (core/cladding diameter $50{\mu}m/125{\mu}m$) and two 1.25" throw-tube couplers. The lens for collimating and imaging is a general purpose focal length 50 mm camera lens (f/1.8). The device for optical path control is a rectangular prism (size $25mm{\times}25mm$). The imaging camera sensor is a Meade DSI Pro 2 CCD sensor (black and white, $752{\times}582$ pixels and pixel size $8.3{\mu}m{\times}8.6{\mu}m$). Softwares for data logging and analysis consist of Meade Autostar Suite, NIH imagej and Vernier Logger Pro 3. The wavelength coverage range of the spectrometer is 205 nm at central wavelength 550 nm. The wavelength resolution is 1.7 nm.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.353-354
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.188-189
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• 2001

광통신 분야에서 파장분할 방식(WDM)이 널리 이용됨에 따라, 파장 가감기는 광통신의 핵심 소자로 주목받고 있다. 특히, 광섬유 브래그 격자를 이용한 전광섬유(All-fiber) 소자는 좁은 선택파장 특성을 만족시키며 삽입손실이 작다는 장점을 가지고 있다. 본 논문에서는 기울어진 광섬유 브래그 격자(Tilted FBG)와 모드분할 방향성 결합기(Mode Selective Coupler, MSC)의 광섬유 공간모드(spatial mode)결합을 이용한 전광섬유 파장 가감기에 대하여 설명하고 있으며, 보다 좋은 성능의 소자제작을 위해 몇 가지 새로운 제작방법을 제안하고 구현하였다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.357-364
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• 2014

In this paper deals with PON Remote monitoring solution using Reflecting Filter. The current FTTH-PON can not be monitored in real time that Optical cable fault and Quality degradation of Splitter. To solve this problem, Monitoring can make Feeder Network and Splitter that Reflecting filter development using the basic structure of Fiber Bragg grating. Reflecting Filter is Quality Monitoring System shall provide tools for user to view and analyze degradation of cables and splitter in particular predict any gradual component degradation(Optical cable bending, splice, connector, etc) before it becomes service impacting. The Reflecting Filter solution is splitter down and confirm the fault location of optical cable and it will send central control station can be monitored system an alarm to the OLT. In other words, wavelength side branches Mating existing communication affairs (Coupler) using the core of one optical wavelength for live monitoring two wavelengths and sends the subscriber side modem and aggregation switch device remotely using a reflective optical line filter monitoring the study of the system. this study can development of Reflecting filter improve the average processing time of Optical cable fault and efficient Maintenance of the network.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.149-153
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• 1997

We demonstrate the operating characteristics(center wavelength, bandwidth, TE/TM polarization, tuning range) of grating-assisted co-directional coupler(GACC) filter fabricated with InGaAsP compound semiconductor. A design of waveguide structure has been focused on the narrow bandwidth characteristics of the filter. Reactive ion etching technique was employed for the uniform waveguide formation. The bandwidths(FWHM) and center wavelengths of the fabricated GACC filter were measured by 1.5 nm and 1530.6 nm for TE polarization and 1.3 nm and 1494.0 nm for TM polarization. This is the one of the narrowest bandwidth at 1530 nm region ever reported. The center wavelength shifted form 1530 nm to 1538 nm when the current of 100 mA was injected at 4.5 mm-long device. Good agreement between the designed and measured operating characteristics for some waveguide structures is demonstrated.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.45-53
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• 1999

Electromagnetic scattering by finite number of conducting strips loaded on a grounded dielectric is considered for the TM polarization case from the viewpoints of transmitting(receiving) leaky wave antenna and grating coupler. An integro-differential equation whose unknowns are the induced currents over the strips is derived and solved by use of the method of moments. In order to construct the non-uniform leaky wave structures with specific source(current) distributions over the strips, distances between two adjacent strips and strip width are simultaneously varied along the structure. From some results for the current distributions over the strips and surface wave powers, it is observed that the maximum coupling efficiencies of the appropriately constructed non-uniform leaky wave structures from the viewpoints of both a receiving leaky wave antenna and a grating coupler amount upto 95%, which are about 15% improvements compared with those(80%) of the uniform structures.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.578-582
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• 2003

We propose a novel structure of wavelength selective optical add/drop module comprising two tap couplers and a fiber Bragg grating. The device has unique features including a simpler structure and a lower cost of implementation as compared with existing devices for the same operation. The module performance has been measured and analyzed experimentally. The implemented prototype module shows good performance with no-crosstalk power penalty in a 155 Mbps per channel wavelength-division-multiplexing transmission system but suffers from a relatively high loss of 3.5 ㏈ and 21 ㏈ for transmitted and dropped channels, respectively. While the dropped channel extinction ratio was more than 25 ㏈, the transmitted channel extinction ratio was more than 35 ㏈.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.656-658
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• 1997

AWG designed in this paper is considered with flat passband characteristics in the channel as a method for solving frequency stability problems of the sources in the conventional optical filters. This device can acquire the flat passband characteristics by inserting the multimode wave guides utilizing the self imaging effec between input wave guides and first star coupler. BPM simulation results show that the excess loss is smaller than 6.5 dB, the crosstalk is less than -22 dB and the 1 dB passband is about 50 GHz in the central channel.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.12-20
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• 1998

The non-uniform leaky wave structure of the slits in a parallel-plate waveguide is analyzed from the viewpoints of transmitting(receiving) leaky wave antenna and grating coupler. Period and slit width are simultaneously varied along the leaky wave structure to construct the leaky wave structure with a specific distribution of complex propagation constant. Some results for the equivalent magnetic current distributions over the slits and the radiation characteristics of the leaky wave structure with various source(equivalent magnetic current) distributions such as Gaussian, uniform, cosine, cosine-squared, and Taylor distributions are given and compared with each other.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.287-291
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• 2013

The low- frequency hydrophone sensor, using the recently developed FBG has an excellent merits which the existing fiber-optic sensor has and also it has an excellent signal sensing effect in the environment of low-frequency(30Hz-300Hz), not to be detected by the PZT sensor. we have the detection of frequency 19KHz right signals when was using more Hopper lenz WDM than $1{\times}3$ optical coupler. furthermore, we can expect the uitilization of low-frequency signal detection to be used for the military purpose and also it can be developed as the high-sensibility multiplexing through the sensor array system.