• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1220-1225
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• 2009

In this paper, a tunable fiber feedback laser based on the use of Sagnac loop filter and fiber Bragg grating (FBG) is proposed. The Sagnac loop filter using a high birefringence fiber provides precise 0.33-nm channel spacing as a multi-wavelength grid filter. Ni-Cr wire wound on the FBG is useful to induce the thermo-optic effect of the fiber. Two types of FBG structures, which have a different length of wire, are demonstrated to show the wavelength shift and separation. To tune FBG by resistant heat, some current is supplied into the wire. When the wavelength matched with one of the cavity modes of Sagnac loop filter, the mode-locked lasing is occurred. The electrical power sensitivity of the resonant wavelength is measured to 1.75pm/mW. This laser configuration can be applied the electrical power system for monitoring the power fluctuation.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.340-344
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• 1997

We proposed and demonstrated a tunable wavelength optical add/drop multiplexer(OADM) employing piezoactuated fiber grating pairs and polarization beam splitters. We used piezostack act as a fiber stretcher, using the fact that the resonant wavelength of the grating can be controlled by the axial strain along the fiber grating. The polarization controlled configuration showed high stability because the reflected signals from the two identical gratings are dropped or added not by interference but by polarizations of the beams. We could add and drop not noly 1549.3nm signal channel(original gratings), but also 1550.1nm(tuned gratings) with PZT actuators and in both cases, we found that the rejection of adjacent channels was more than -26dB, and signal leakage at the gratings was less than -34dB.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.155-161
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• 1990

A Continous wave tunable $CO_2$ laser which is the slow axial flow type was construccted for the optical pumping of methyl alcohol ($CH_3OH$) laser. The reflective grating of 100 grooveslmm and 10.6$\mu\textrm{m}$ blaze wavelength was used to select wavelength. We have investigated continous outpu: power characteristics, and then have compared tuned output power profile with the gain curve of $CO_2$ laser. The optimum condition for maxium power was found at the gas mixing ratio 1 : 3 : 10 for $CO_2: N_2$ and He. under this condition the flow rate, pressure of lasing gas and discharge current are 9.5 llmin. 14 torr, and 55 mA respectively. The maxium output power was 55 Wlm. Output power of single wavelength operation was measured on 60 individual rotation vibration transitions in the P and K branches of the 9.5$\mu\textrm{m}$ band and 10.4$\mu\textrm{m}$ band in $CO_2$. The output power profile obtained from each band is well consistent with the gain curve of $CO_2$ laser and maxium tuned output power was 20 watt.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12A
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• pp.1177-1181
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• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.10 s.340
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• pp.19-28
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• 2005

In this paper, we analyzed tuning characteristics of the widely tunable SGDFB laser diode integrated with SGDBR. The improved time-domain model is used to analyse the laser diode. From the numerical analysis, the length of phase control region in the SGDFB section influences on the output power and the tuning range. Also, it was confirmed that the tuning range is affected by the length of the laser diode, the residual reflectivity at the facet, and the position of the facet.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.219-223
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• 2008

To realize a widely tunable laser diode, a polymer coupled-ring reflector is hybrid- integrated with reflective semiconductor optical amplifier. Even though ring-ring and ring-bus coupling ratios are changed by fabrication errors in waveguide width and height, they remain very close to the single peak condition, ensuring high yield in fabrication. The tuning range is observed to be about 35 nm, maintaining the side mode suppression ratio of about 30 dB.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1826-1828
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• 2001

본 논문에서는 주기적으로 홈을 새긴 V자 홈과 평판 사이에 광섬유를 놓고 압력을 인가함으로써 유도되는 파장가변 가능한 장주기 광섬유격자의 제작 및 특성에 대해서 살펴 보았다. 이러한 방식으로 제작된 장주기 광섬유격자의 투과특성 및 모드결합 특성은 기존의 장주기 광섬유격자와 유사한 특성을 보이면서도 모드결합이 일어나는 중심파장을 거의 180nm 이상으로 가변할 수 있었다.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.171-180
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• 1998

The low cost fiber ring laser can be tuned by controlling polarization states within the loop. In this paper, we investigate its operating principle and verify the performance through an experiment. This ring laser consists of a polarization controller and an intracavity polarizer for the wavelength tuner and semiconductor optical amplifier for the gain medium. It is seen that the lasing wavelength may be tuned through the range of 1540~1560 nm as a polarization controller and a polarizer are adjusted.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.99-102
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• 2005

We fabricated a tunable fiber ring laser consisting of a novel strain device and fiber Bragg gratings. The lasing power and FWHM bandwidth of the optical fiber ring laser was -12dBm and 0.05nm respectively. The fiber ring laser was tuned as much as 10nm at a 8000.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.143-149
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• 2001

We performed the intracavity frequency-doubling of a tunable continuous-wave Ti:sapphire laser using a lithium triborate $(LiB_3O_5, LBO)$ crystal. For an efficient intracavity frequency-doubling, we measured the spectral and the angular bandwidth about the $\theta$-direction of LBO crystal. The measured values at a fundamental wavelength of 800 nm were 1.54 nm.cm and 3.8 mrad.cm, respectively. As a result of an intracavity frequency-doubling, we obtained the second-harmonic generation output power of 5.3 mW at 400 nm with the full width at half maximum(FWHM) of 0.089 nm from the fundamental output power of 185 mW at 800 nm. The frequency-doubled output was tuned from 397 nm to 403 nm.403 nm.