• 전자공학회논문지D
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• 제34D권6호
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• pp.58-64
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• 1997

The wavelengt lockin gsystem of the optical fabry-perot filter theoretially derived and experimentally realized by using the ithering method in order to compensate the laser wavelength drift increasing the BER of the WDM system. The deviation between the laser wavelength and the optical filter center wavelength is compensated by applying a suitable voltage to the PZT. Accordingly, the laser wavelength selected by the fabry-perot filter always maintains the condition of maximum transmission powr. A wavelength locking system has been demonstrated using a fiber fabry-perot filter with a free spectral range of 80nm and an FWH of 1nm. The voltages of the sine wave generated for dithering was 20mV and 10mV, the frequency was 2kHz and center wavelength of the tunable laser was 1550nm. In this paper, the locking system have 20ms of locking time and 2nm of locking range.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.33-37
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• 2010

In this paper, we have demonstrated absolute wavelength tuning in an optical fiber comb filter based on a polarization-diversity loop configuration by controlling the current injected into enameled wires wound on polarization-maintaining fibers (PMF's), that is, adjusting Joule heat generated from enameled wires. The proposed fiber comb filter consists of a polarization beam splitter, a half-wave plate, a quarter-wave plate, and PMF's. And we observed wavelength change of spectral dips in transmission spectra of the fabricated filter by varying an input current applied to enameled wires. The absolute wavelength of the filter could be controlled in proportional to the square of the input current with good linearity, and the rate of the wavelength shift with respect to the input current was measured as 36.79[nm/$A^2$].

• 전기학회논문지
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• 제58권7호
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• pp.1393-1397
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• 2009

A high-speed wavelength swept laser, which is based on oscillation characteristics of a fiber Fabry-Perot tunable filter, is described. The laser is constructed by using a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, and 3.348 km fiber ring cavity. The wavelength sweeps are repeatatively generated with the repetition period of 61 kHz which is the first parallel oscillation frequency of the Fabry-Perot tunable filter for the low power consumption. Mode-locking is implemented by 3.348 km fiber ring cavity for matching the fundamental of cavity roundtrip time to the sweep period. The wavelength tuning range of the laser is 87 nm(FWHM) and the average output power is 1.284 mW.

• 전기학회논문지
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• 제56권6호
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• pp.1117-1121
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• 2007

We demonstrate a wavelength swept mode-locked ring laser for the frequency domain optical coherence tomography(FD OCT). A laser is constructed by using a semiconductor optical amplifier, fiber Fabry-Perot tunable filter and 2.6 km fiber ring cavity. Mode-locking is implemented by 2.6 km fiber ring cavity for matching the fundamental or harmonic of cavity roundtrip time to a sweep period. The wavelength sweeps are repetitively generated with the repetition period of 77.2 kHz which is the parallel resonance frequency of Fabry-Perot tunable filter for the low driving current consumption of the fiber Fabry-Perot tunable filter. The wavelength tuning range of the laser is more than FWHM of 61 nm centered at the wavelength of 1320 nm and the linewidth of the source is $0.014{\pm}0.002$ nm.

• 한국광학회지
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• 제26권6호
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• pp.306-311
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• 2015

본 논문은 폴리머 광 도파로 기반의 브라그 격자(Polymer waveguide Bragg grating: PWBG) 파장 필터를 광섬유 레이저 공진기 내부에 삽입하여 단일 파장 가변 레이저를 구현하고, 주위 온도 및 공진기 내부의 편광 상태의 변화에 대한 출력 특성을 연구한 결과에 대해 보고한다. 레이저 공진기 내부에 있는 PWBG 파장 필터에 0 mW에서 100 mW의 전력을 인가해 주었을 때 레이저에서 발진하는 파장은 1548.24 nm에서 1531.95 nm까지 약 16.29 nm를 가변할 수 있었으며, 이 때 slope efficiency는 약 -0.16 nm/mW였다. 레이저 공진기 안의 편광을 적절하게 조절하면 모든 파장 가변 범위에서 35 dB 이상의 SMSR(side mode suppression ratio)을 얻을 수 있었다. 레이저 공진기 외부의 온도가 변화하면 발진하는 파장이 변하는 것을 알 수 있었다. 따라서 PWBG 파장 필터를 이용하여 안정된 파장 가변 레이저를 구현하기 위해서는 PWBG 파장 필터의 온도 안정화가 필요하며, 또한 편광에 대한 영향을 최소화하기 위해서는 레이저 공진기를 편광유지 광섬유로 구성해야 한다.

• 한국통신학회논문지
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• 제28권8A호
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• pp.657-662
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• 2003

광성능을 모니터하기 위해 필요한 것이 OPM(optical performance monitoring module)이다. OPM에서 가장 중요한 것은 광 신호의 파장을 측정하는 것이다. 기존에는 pilot tone을 사용하였으므로 파장값을 얻기가 어려웠지만, 그후 AWG(arrayed waveguide grating), AOTF (acousto optic tuneable filter) 등을 사용하여 다채널 신호에 대한 파장과 전송 품질을 모니터하게 되었다. 본 논문에서는 일반적으로 광 분해능이 우수하다고 평가되는 FFP-TF(fiber fabry perot tuneable filter)를 채택하였으며, FFP-TF를 사용하기 때문에 필요한 기준파장의 설정을 위하여 광섬유격자(FBG : fiber bragg grating)를 사용하였다.

• Current Optics and Photonics
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• 제1권6호
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• pp.579-586
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• 2017

In this paper, we theoretically demonstrate that semiconductor optical amplifiers (SOAs) with strong wavelength dependence of gain and phase are capable of all-optical inverted and non-inverted wavelength conversion (WC) over a wide range, with the assistance of an optical filter. First, the gain dynamics and phase dynamics in a common quantum well (QW) SOA with the $In_{0.53}Ga_{0.47}As/In_{0.7322}Ga_{0.2678}As_{0.5810}P_{0.4190}$ material system are found to be strongly dependent on wavelength, which is mainly related to the wavelength dependence of the differential gain and the differential refractive-index change. Second, the wavelength dependence in an all-optical wavelength converter based on the QW SOA cascaded with a detuning band pass filter is studied. Simulations show that the quality of the converted signal has little dependence on the operation wavelength. Both inverted and non-inverted WC can be achieved, over a large wavelength range. Therefore, although the gain and phase change are strongly wavelength-dependent, the effects of this dependence can be erased by appropriate optical filtering.

• Journal of the Optical Society of Korea
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• 제13권3호
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• pp.330-334
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• 2009

A simple and compact frequency swept laser is demonstrated at $1.3{\mu}m$ using a wavelength scanning filter based on a rotating slit disk. The laser is comprised of a pigtailed semiconductor optical amplifier, a circulator, and a wavelength scanning filter in an extended cavity configuration. The wavelength scanning filter is composed of a collimator, a diffraction grating, a rotating slit disk, and a mirror. The instantaneous laser output power is more than 5 mW. The scanning range of the laser is extended to 80 nm at the maximum level, and 55 nm in the full width at half maximum at a scanning rate of 2 kHz.

• 한국통신학회논문지
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• 제23권4호
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• pp.1051-1058
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• 1998

광굴절결정에서 두 기록빔의 입사각에 따른 파장선택성을 이용해 원하는 통과대역과 중심파장을 갖는 대역통과필터로의 응용을 제안하였다. 2광파결합을 통해 Fe가 0.02Wt.% 도핑된 $LiNbO_3$ 결정의 회절특성을 실험함으로써, 가장 우수한 회절효율을 갖는 조건을 도출하고, 이러한 조건에서 원하는 대역 및 파장을 선택해 낼 수 있는 대역통과필터를 전광학적으로 구현하였다. 또한, 기록빔의 입사각을 변화시킴으로써, 임의의 원하는 필터 특성을 얻을 수 있음을 실험적으로 증명하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권5호
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• pp.267-271
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• 2006

A polymeric waveguide-type wavelength filter based on a Bragg grating has been proposed and fabricated using the simple nanoimpring technique, for the first time to our knowledge. An ultraviolet transparent stamp with the single-mode waveguide pattern incorporating a surface-relief-type Bragg grating was specially designed selective dry-etching process. Using this stamp, the device fabrication was substantially involving just a single-step process of imprint followed by polymer spin-coating. The achieved maximum reflection was higher than 25 dB at the center wavelength of 1569 nm. And the 3-dB bandwidth was 0.8 nm for the device length of 1.5 cm.