다중모드 간섭현상을 이용한 1 × 16 마하젠더 스위치 개발

김성원,홍종균,이상선 한국광학회 2006 한국광학회지 Vol.17 No.5

A 1×16 thermo-optic switch with small excess loss using multimode interference(MMI) couplers is designed, fabricated, and measured. This paper introduces the proposed 1×16 thermo-optic switch, and discusses the measurement results. The 1×16 thermo-optic switch is formed as 4-stage which consists of 15 unit devices. The unit devices are the 2×2 thermo-optic switches with Mach-Zehnder interferometer(MZI) structure. The characteristics of the 1×16 thermo-optic switch depends strongly on each unit device. The unit deviceconsists of two 3-dB general interference MMI couplers and two single mode waveguide arms as a phase shifter. First of all, the 3-dB optical splitter and 2×2 MZI thermo-optic switch have been tested to confirm the characteristics of the unit devices of the 1×16 MZI thermo-optic switch. Using the measurement results of the unit devices, the 1×16 MZI thermo-optic switch can be produced with better characteristics. The resultant structure of the MMI coupler with the optical light source of wavelength of 1550nm for the 1×16 thermo-optic switch is that the width and the optimized length are 25μm and 1580μm, respectively. The smallest excess loss for the unit device is -0.5dB and the average excess loss is -0.7dB.

Cr4+ : YAG 레이저에서 열 렌즈 효과에 따른 공진기의 안정영역과 빔 허리 및 비점수차의 보상

이봉연 한국광학회 2006 한국광학회지 Vol.17 No.5

We obtained analytic solutions of boundary conditions to the stable region of Z-fold Cr4+ :YAG laser cavity when the conditions are with and without thermal lensing effect. Also we investigated the influence of the thermal lensing effect on the stability of cavity, beam waist, and astigmatic compensation using aberration transformation matrices. The thermal lensing effect almost has no influence on the stable region of the cavity when the crystal is located in the middle of two concave mirrors and when the distances from the concave mirror to the reflecting mirror and the output coupler are the same. The beam waist, however, is affected more in a tangential plane than in a sagittal plane, and so it is difficult to have astigmatic compensation when the thermal lensing effect exists. This result means that the thermal lensing effect should be considered even for the Kerr-lens mode-locking.

위상변조가 쌍안경 대물경 OTF에 미치는 영향

홍경희 한국광학회 1993 한국광학회지 Vol.4 No.1

We investigate the phase modulation effects on the OTFs of a binocular objective which is made in Korea.The OTFs are calculated from design data for FOV $0^{\circ}$ and $1.5^{\circ}$.The phase modulation is carried out by giving phase retardation $\pi$ on the aperture. The areas where the phases are retarded $\pi$ on the aperture are of an annular type. The OTFs of phase modulated aperture are also compared with that of unmodulated one. The OTFs of an aberration loaded system can be improved by proper phase modulation.

분할디스크형 글라스레이저 증폭기의 온도분포특성에 관한 연구

김병태 한국광학회 1992 한국광학회지 Vol.3 No.4

The simulation code was developed for the development of the split-disk geometry glass amplifier, which could design the laser apparatus and analyze the properties of the laser system. The flashlamp emission energy at the short wavelength region must be reduced, while maintaining a current density between 2000 and 4000 A/$\textrm{cm}^{2}$, in order to reduce the thermal loading in the laser glass and to raise the coupling efficiency between the emission spectrum of the flashlamps and the absorption spectrum of the laser glass. By cutting the laser glass into three equal pieces, the temperature rise in the laser glass dropped by 70% due to the efficient removal of the heat in the laser glass. It was found that the $Nd^{3+}$ doping rate of each laser glass should be properly selected and the optimum value of the product of the absorption coefficient $\alpha$ and the thickness d of the laser glass is about 0.26 in the split-disk geometry.

$Ar^+$ 레이저로 펌핑되는 Nd:glass 레이저의 발진특성

이종무,강응철,남창희 한국광학회 1992 한국광학회지 Vol.3 No.4

$Ar^{+}$레이저로 펌핑되는 Nd:glass레이저를 제작하여 그 특성을 조사하였다. 레이저 공진기는 오목거울 두 개와 98% 고반사 평면경, 그리고 Brewster 각도로 놓인 Nd:glass 의 이득 매질로 구성되었으며, 효율적인 펌핑을 위해서 $Ar^{+}$레이저 광선을 공진기 길이 방향으로 입사하여 공진모우드의 beam waist에서 초점이 맺히도록 하였다. Nd:glass의 열존도도가 작아서 흡수된 펌핑빔에 의해 생성된 잔열로 인한 매질의 손상이 우려되기 때문에 mechanical chopper 로 펌핑빔을 100Hz로 끊어서 입사하여 잔열의 생성을 줄였다. 1.5W로 펌핑될 때 Nd:glass 레이저의 출력은 70mW이었고 발진이 되는 문턱에서의 펌핑파워는 520mW이었으며 slope efficiency는 7.4%이었다.

대용향 광 연상기억을 위한 대칭 삼층구조의 구현

서호형,이상수 한국광학회 1992 한국광학회지 Vol.3 No.3

We have developed a new optical associative memory system hased on the symmetric three layered neural network model, uhing two holograms and a LCIV. In the experiment, four Korean alphabet letters (ㄹ, ㅅ, ㅇ, ㅈ) are used as memory patterns. The results are compared with those of the two layered network and the IIopfield models. The results show that more than 95% recognition ablity is obtained for thc input which has the error rate less than 12%.

금속증기레이저 연구 II

이재경,정환재,임기건,이형종,정창섭,김진승 한국광학회 1992 한국광학회지 Vol.3 No.3

An air-cooled discharge-heated copper-vapor laser system with its inter-electrode distance of 45 cm has been developed by utilizing an alumina ceramic plasma tube of 1.6 cm in diameter and 50 cm in lengih. For operating the laser, a dc high voltage power supply with output rating of 6 kV and 500 mA, a resonant charging circuitry consisting partly of an 1.8 H inductor assembly and a 5 nF storage capacitor, and a thyratron driver operating up to 7 kHz have also been developed. The present laser system starts lasing at the tube temperature of about $1350^{\circ}C$ and an maximum average output power of 0.7 W has been obtained at 12 kV, 4.5 kHz. 50 mbar of Ne buffer gas pressure, and at the tube temperature of $1460^{\circ}C$.

광통신 변조기용 미세광학소자의 설계

홍경희 한국광학회 1992 한국광학회지 Vol.3 No.4

A micro lens system was designed for the modulator in optical fiber communication. One was the collimating lens which transferred the diffracted beam from optical fiber to the modulator. The other was the coupling lens which connected the modulated collimating beam to the optical fiber. The light source was He-Ne laser beam. The lens would be made of optical glass BK-7. We determined the tolerance of curvature radius, thickness and conic constant.

비선형 광신호의 간섭현상 연구

이은성,한재원,박승남,이충희 한국광학회 1992 한국광학회지 Vol.3 No.4

We have investigeted the interference phenomena of the second harmonic waves of Nd:YAG laser generated at KDP single crystals and the nitrogen CARS signals. To get the phase difference between the successively generated nonlinear optical signals, a phase shifting unit made of BK-7 glass and a high pressure gas cell are used. Coherence lengths of several samples for the nonlinear signals are measured. Adjusting the thickness of the phase shifting unit where the CARS signals make destructive interference completely, the CARS spectrum of nitrogen suppressed over wide wavelength range is obtained. Also, we have observed the change in degree of suppression of the spectrum for the variation of the thickeness of the phase shifting unit.

CARS를 이용한 화염내부 온도분포 측정연구

한재원,박승암,이은성,이충희,강경태,정석호 한국광학회 1992 한국광학회지 Vol.3 No.4

A coherent anti-Stokes Raman spectroscopy (CARS) technique is applied to measure temperature profile in a flame. The CARS signal is obtained with BOXCARS phase matching to get better spatial resolution. A program routine for calculating temperature of the flame from the measured CARS spectra is studied. The routine includes the line broadening mechnism of the molecules described with a modified energy gap (MEG) law by using the perturbation theory. We have found that the temperature profile obtained with the MEG law is properly fit with the results measured with a thermocoulpe and calculated with the adiabatic theory.