• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.38-43
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• 2014

An external cavity laser supporting two wavelengths is demonstrated by incorporating polymer waveguide Bragg reflectors and a superluminescent light-emitting diode. An oversized rib waveguide structure and Bragg gratings are designed by using the effective-index and transmission-matrix methods. Bragg gratings with different periods are inscribed on a polymer waveguide through double-exposure laser interferometry. In order to tune the cavity loss affected by the reflectivity of Bragg gratings, a Bragg reflectors with varying length is incorporated. Two-wavelength-mode lasing is achieved for the device consisting of 2-mm long, 537-nm period gratings and 2.2-mm long, 540-nm period gratings; the lasing wavelengths are 1554 nm and 1564 nm, with an output power close to 0 dBm, a 20-dB bandwidth of 0.2 nm, and a side-mode suppression ratio of 45 dB.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.299-300
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.188-189
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.92-93
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• 2002

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1113-1120
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• 2014

In this paper, general methods for enhancing the transmission efficiency through the small subwavelength aperture in an infinite conducting plane are considered first by use of the transmission-resonant aperture like the ridged circular aperture structure, second by employing the transmission-resonant cavity structure. In particular, the maximum transmission cross section is found to be $\frac{2G{\lambda}^2}{4{\pi}}[m^2]$ for the two structures, where G is the gain of the aperture in the output half space. As experimental works, the impedance matching characteristics are investigated for the cases that above two structures are incorporated as a potential near field microscopic probe in the waveguide end. As a complementary problem to the above transmission-resonant aperture problem, some discussions are also given on the scattering resonance by the scattering object much smaller than the wavelength. This discussion may provide a good understanding of the physics for the phenomena that the maximum scattering cross section is much larger than the physical size of the atom in atomic physics area.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.347-355
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• 2002

We have constructed a high efficiency and broad tunable cw Ti:sapphire laser with a four-mirror symmetric Z-type laser cavity to increase the laser usability. From theoretical analyses and experimental data for a symmetric Z-type laser cavity containing a Kerr medium, the cavity mode size and the Kerr-lens mode-locking (KLM) strength for KLM lasers can be confirmed as function of the position in the cavity, the intracavity laser power, and the stability parameter. As a result, the slope efficiency and the maximum average output power of cw Ti:sapphire laser at 5 W pumping power of Ar-ion laser were 31.3% and 1420 ㎽ respectively. The tunablility was ranged from 730 ㎚ to 908 ㎚ with average output power above 700 ㎽. We obtained the KLM operation easily by self-aperturing effect in the Kerr medium and the slope efficiency and the maximum average output power of KLM Ti:sapphire laser was 16% and 550 ㎽ respectively. The spectral bandwidth was 33 ㎚ at the center wavelength of 807 ㎚ and the pulse width was 27 fs with a repetition rate of 82 ㎒.

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.156-162
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• 2001

Novel pressure sensor using the resonance wavelength shift of single mode fiber-to-planar waveguide coupler, was demonstrated. It is found that the resonance wavelength shift due to refractive index variation of polymers by pressure occurs and its sensitivity depends on materials. We adopted symmetric structure of planar waveguide and remove the polarization dependence which is inevitable with side-polished fiber. AZ4562, AZl512 and THB-30 are used as planar waveguide materials and the resonance wavelength shifting by pressure was shown -0.008um/bar, 0.033nm/bar and 0.16nm/bar, respectively.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.15-21
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• 2000

Optical fiber temperature sensor, using resonance wavelength shifting of single mode fiber-to-planar waveguide coupler by heat, was fabricated. Thermo-optic polymers, have large change of refractive index due to heat, were used for planar waveguide. The device fabrication procedure including fiber polishing steps was illustrated and the device structure with independent polarization was demonstrated experimentally. The resonance wavelength difference of fabricated device was less than 2nm. The resonance wavelength shifting owing to temperature variation, from room temperature($24^{\circ}C$) to $90^{\circ}C$, was showed $-0.54nm/^{\circ}C$, $-3nm/^{\circ}C$.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.70-71
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• 2002

다이오드 여기 고체레이저(DPSSL, Diode-Pumped Solid State Laser)는 레이저 마킹기, 미세가공기, Ti：sapphire 및 각종 레이저 매질 여기, 의료기기, 그리고 군사용 계측기 등에 다양하게 사용되고 있다. 이러한 응용분야들에 효과적으로 사용되기 위해서는 레이저 출력, 빔모드, 펄스폭, 파장 등이 응용분야에 적합하도록 설계되어야 하며, 고반사율을 갖는 금속의 가공 및 마킹, 그리고 몇가지 레이저 매질의 여기원으로 사용되기 위해서는 짧은 펄스폭과 고품질을 갖는 녹색 파장의 DPSSL 개발이 필요하다. (중략)

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.80-83
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• 1994

A Littman type dye laser oscillator inserted a wedge prism was constructed. Accurate frequency tuning was achieved by the rotation of the wedge prism instead of the tuning mirror. Frequency tuning rate was about 20 GHz/deg. and the synchronous tuning of 70 GHz without mode-hop was achieved. ieved.