• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.96-97
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• 2000

Incoherent broadband optical sources have been applied in various areas such as a light source for optical device characterization, fiber-optic gyroscopes$^{(1)}$ , and spectrum sliced light source in wavelength division multiplexing (WDM) system$^{(2)}$ . To utilize the inherent low loss in silica optical fibers, various types of incoherent light sources are being developed. Among the light sources, the amplified spontaneous emission (ASE) from a rare earth doped fiber has benefits in temperature stability, high output power, low polarization dependence over semiconductor diodes$^{(3)}$ . Recently erbium doped fibers (EDF) have been intensively researched for ASE sources as well as optical amplifiers$^{(4)}$ . The spectrum of ASE from an EDF, however, is limited in the 1520~1560 nm range in conventional configurations. In this letter we described a new broadband ASE source which included both the conventional ASE band of Er$^{3+}$ ion, 1520nm~1560nm and ASE band from Tm$^{3+}$ ions that extends the bandwidth further. For the first time, to the best knowledge of authors, a fiber ASE source based on the energy transfer between Er$^{3+}$ and Tm$^{3+}$ ions in the range of 1460~1550 nm, has been demonstrated using a single 980nm pump laser diode. (omitted)omitted)

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.222-226
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• 2011

We demonstrated the feasibility of an amplified wavelength-division multiplexed passive optical network (WDM-PON) architecture based on broadband light source (BLS) seeded optical sources and a novel bidirectional reach extender. Our bidirectional reach extender could provide an amplification of both downstream and upstream signals as well as a BLS output for the upstream WDM signal generation. An error-free 1.25 Gb/s signal transmission over a 100-km long single-mode fiber was achieved in a bidirectional WDM-PON using BLS seeded reflective semiconductor optical amplifier (RSOA) sources.

• ETRI Journal
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• 제27권3호
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• pp.334-336
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• 2005

We improved the performance of the spectrum-sliced light source for wavelength-division-multiplexed passive optical networks by employing a Fabry-Perot laser diode(FP-LD). We found that the FP-LDs can suppress the intensity noise as significantly as using a gain-saturated semiconductor optical amplifier. The transmission characteristics were measured and analyzed in both conditions with and without employing an FP-LD.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.4-8
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• 2011

We have evaluated the performances of bidirectional optical amplifiers which were suited for the cost-effective implementation of amplified bidirectional passive optical networks (PONs). First, we measured the maximum gains of two simple bidirectional optical amplifiers implemented without using any optical components for the suppression of reflected signals. From the results, the maximum gains of two simple bidirectional amplifiers with a broadband light source (BLS) seeded optical source were limited to be 27 dB due to the reflection-induced in-band crosstalk, when the reflectance coefficients were measured to be -33 dB in both directions. Then, we have also implemented a bidirectional optical amplifier with two band splitters for the amplified bidirectional PON where the two different wavelength bands were allocated to the downstream and upstream signals transmission. In our measurement, we confirmed that the maximum gain of bidirectional optical amplifier with two band splitters could be increased to more than 30 dB owing to the efficient suppression of in-band crosstalk.

• 한국통신학회논문지
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• 제25권3B호
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• pp.504-509
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• 2000

This paper presents a noble operation and maintenance system for the optical subscriber loops and its feasibility through several experiments. In this system, a broadband CW (Continuous Wave) light source I used as monitoring of testing signals. and a FGF(Fiber Grating Filter) of which reflective wavelength is independent, is inserted somewhere in each subscriber loop for the reflection of monitoring of testing signals. The propose of the system is quick decision. whether the loop is just fault or not. rather than detailed information of loop state. At present, most of operation and maintenance system for the optical subscriber loops adopts OTDR(optical time domain reflectometer) for testing function. the OTDR is useful for detailed test, but not adequate for simple test because of long testing time . And it is difficult to test PON network by using general OTDR that has a single-wavelength light source. Compared to using OTDR, the proposed system can afford to shorten testing time and to test PON network. Moreover, we can cut down the system cost by simplifying circuits of the optical light sources. Our results show that the proposed system operates well according to the purpose mentioned above.

• 한국통신학회논문지
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• 제22권2호
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• pp.371-380
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• 1997

초고속 광가입자망을 효율적으로 구축하지 위한 많은 연구가 이루어져 오고 있는 가운데, 본고에서는 이를 위한 한 방안으로 공유광원 및 원격변조방법을 이용한 광가입자망 전송시스템을 제안하고 기술적, 경제적 타당성을 고찰한다. 제안된 시스템에서는 상하향 전송링크에 외부변조방식을 채택하고 전송에 필요한 모든 캐리어 광원은 전화국에서 공급된다. 또한 캐리어 광원은 각각의 링크별로 두지 않고 소수의 광원을 다수의 링크가 공유하는 구조로 되어 있다. 본 시스템에 대한 실험적 시뮬레이션 결과, 하나의 공유광원으로 하향전송(2.5Gb/s)시에는 약 2,000 가입자링크의 수용이 가능하고 상향전송(155Mb/s)시에는 약 500 가입자링크를 수용할 수 있음을 알았다.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1481-1488
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• 1995

Due to the low loss, broadband and accurate short time delay properties of optical fiber, it has attracted as a delay medium for high speed and broad-band signal processing. In this paper, we consider the coherent optical fiber filter of IIR lattice structure, which uses coherent light sources and consists of directional couplers whose coupling coefficients are restricted between 0 and 1. Considering restrictions of directional coupler, the design formulae and condition for realibility of optical fiber filter of IIR lattice structure which makes the optimal use of optical signal energy are derived.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.436-441
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• 2014

We have demonstrated an amplified wavelength-division multiplexed (WDM) passive optical network (PON) by using broadband light source (BLS) seeded optical sources and chirped fiber Bragg gratings (FBGs) based dispersion compensators. Chirped FBGs located at central office (CO) were fabricated and used as channel-by-channel dispersion compensators in order to mitigate the dispersion-induced distortion of both downstream and upstream signals. Owing to a low insertion loss of chirped FBG based dispersion compensator, the optical signal-to-noise ratio (OSNR) of the downstream signal could be improved to be ~28 dB. Thus, we re-confirmed that an error-free transmission of 1.25 Gb/s signals over a 100 km single-mode fiber (SMF) link could be achieved with a proposed amplified WDM-PON architecture. We have also evaluated the impact of various noises on the system's performance, and found that the low OSNR of the downstream signal would be a main limiting factor on the maximum reach of the proposed amplified WDM-PON architecture. From the measured ~13 dB improvement in OSNR of the downstream signal compared to our previously-proposed dispersion compensating module based scheme, we believe that the proposed architecture can accommodate a reach of longer than 100 km SMF link easily.

• 한국광학회지
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• 제21권5호
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• pp.195-199
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• 2010

본 논문에서는 광자결정 광섬유를 이용하여 1000 nm 의 광대역폭을 갖는 광신호 분배기를 구현하였다. 제작에 사용된 광자결정 광섬유의 지름은 $130{\mu}m$ 이고 6층의 공기 구멍 구조로 이루어져 있다. 광신호 분배기는 두 가닥의 광자결정 광섬유에 열을 가함과 동시에 인장력을 가해 제작하였으며 제작된 광자결정 광섬유 기반 광신호 분배기의 지름은 $23{\mu}m$ 이었다. 광신호 분배기의 제작 시 인장시키는 길이에 따라 대역폭과 bandedge가 조절되었다. 제작된 광자결정 광섬유 기반 광신호 분배기의 대역폭이 1000 nm에서 50:50의 광신호 분해 효율을 가지는 것으로 측정되었다. 광자결정 광섬유의 공기 구멍 구조의 특성으로 인해 주변온도의 변화에 영향을 받지 않는 특성을 나타낸다. Optical coherence tomography의 분해능이 광원의 대역폭에 비례하므로 광대역폭을 갖는 광자결정 광섬유 기반 광신호 분배기는 신호 추출을 위한 간섭계 구성에 핵심적으로 활용될 수 있을 것으로 사료된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.53-57
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• 2004

The stabilization of fiber-optic current sensor has been achieved by using a broadband light source and a Faraday Rotator Glass fiber sensor coil. The very low Photo-elastic constant of the fiber suppressed output variations within ${\pm}0.4[%]$ when mechanical disturbance was applied to the sensor coil. Noise characteristics, with different light sources, have also been analyzed, which experimentally proved that the wider bandwidth source showed the better noise performance.