• Journal of the Optical Society of Korea
• /
• 제8권2호
• /
• pp.90-95
• /
• 2004

The structure of Ti:LiNbO$_3$optical waveguide with a mode size far different from that of single mode optical fiber has been optimized by tapering the waveguide ends. This work was focused on determining the optimized sets of parameters for the fabrication of low-loss Ti indiffused optical waveguides in LiNbO$_3$. Numerical and analytical modeling were applied to simulate the guiding quality and to determine the mode sizes. Based on these modeling results, new waveguide structures with tapered ends have been defined, fabricated and characterized in the respect of the coupling of fiber to Ti-indiffused LiNbO$_3$waveguide.

• 한국소음진동공학회논문집
• /
• 제16권9호
• /
• pp.971-981
• /
• 2006

This paper presents the design and characterization of a novel fiber optical coupler for intensity modulated fiber optical microphone. Theoretical equations for the optical power coupling are presented in detail including optical path analysis and misalignment. Various optical couplers are simulated and manufactured. A multi-mode to multi-mode coupler is characterized by static and dynamic movements of mirror on a well designed experimental stage.

• Journal of the Optical Society of Korea
• /
• 제20권2호
• /
• pp.291-299
• /
• 2016

We have investigated the ultimate limits of nonuniform grating couplers (NGCs) for optimized fiber coupling to silicon waveguides, compared to uniform grating couplers (UGCs). Simple grating coupler schemes, which can be fabricated in etching steps of the conventional complementary metal-oxide semiconductor (CMOS) process on silicon-on-insulator (SOI) wafers without forming any additional overlay structure, have been simulated numerically and demonstrated experimentally. Optimum values of the grating period, fill factor, and groove number for ultimate coupling efficiency of the NGCs are determined from finite-difference time-domain (FDTD) simulation, and confirmed with experimentally demonstrated devices by comparison to those for the UGCs. Our simulated results indicate that maximum coupling efficiency of NGCs is possible when the minimum pattern size is below 50 nm, but the experimental value for the maximum coupling efficiency is limited by the attainable fabrication tolerance in a practical device process.

• Journal of the Optical Society of Korea
• /
• 제12권3호
• /
• pp.192-195
• /
• 2008

We report on the spatial information of a coupling laser transfer into a reflected probe laser; the transfer is achieved by means of electromagnetically induced transparency through a common excited state connected with $5S_{1/2}-5P_{1/2}(F=1{\rightarrow}F'=2)$ in the $^{87}Rb\;D_1$ line. When the coupling laser was spatially modulated as a stationary wave, the absorption of the probe laser was enhanced and the reflection of the probe laser was generated. When the coupling laser was spatially modulated by a mask, we observed that the reflection light of the probe laser was modulated as the shape of the mask. The Bragg reflection transferred the spatial information of the coupling laser. The reflection was approximately 7% of the incident power of the probe laser.

• 마이크로전자및패키징학회지
• /
• 제18권1호
• /
• pp.7-13
• /
• 2011

According to increasing of data transfer rate, printed circuit board (PCB) is required improvement of transmission speed. Optical PCB and its packaging technology can be one of the solutions that overcome the limitations of conventional electrical PCB. The data transmission capacity will be increased 10 Tbps at 2015. To this end, studies on various OPCB technologies are being conducted. For cost-effective and high- performance OPCB, studies of optical coupling by polymer replication process are conducted. In this work, optical waveguide and optical fiber array block were sequentially fabricated by polymer pattern replication method. Using this method we successfully demonstrate low loss optical fiber coupling between optical waveguide and optical fiber arrays. And researches on flip chip bonding process and using electro-optic connectors for packaging are conducted.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.552-554
• /
• 1995

In long-haul high speed optical communications, the distance between a transmitter and a receiver depends on the amount of light coupled to a single mode optical fiber from the laser diode(LD) as well as the LD characteristic itself. And the transmitter module must have long lifetime. high reliability, and even simple structure. Such points have induced laser welding technique to be a first choice in opto-electronic module packaging because it can provide strong weld joint in a short time with very small coupling loss. In this paper, packaging considerations and characteristics for high speed LD modules are discussed. They include optical path design factors for larger aligning tolerance, and novel laser welding processes for component assembly. For low coupling loss after laser welding processes, the optical path for optimum coupling of a single mode optical fiber into the LD chip was designed with the GRIN lens system providing sufficiently large aligning tolerance both in the radial and axial directions. The measured sensitivity of the LD module was better than -33.7dBm(back to back) at a BER of $10^{-10}$ with a 2.5Gbps NRZ $2^{23}-1$ PRBS.

• 마이크로전자및패키징학회지
• /
• 제27권4호
• /
• pp.47-54
• /
• 2020

활성 도파로와 수동 도파로의 집적은 광집적 회로의 구성에서 필수적인 요소이다. 이를 구현하기 위한 여러 기술 중 버트 조인트는 상당한 장점을 가지고 있다. 그러나 버트 조인트 접합은 높은 광손실을 야기하며, 두 도파로 간의 정렬에 있어서 정확한 공정 제어가 요구되는 구조이다. 본 논문에서는 레이저 다이오드와 spot size converter (SSC)로 구성된 집적 소자를 시뮬레이션하기 위해 beam propagation method을 이용하였다. 상이한 모드 특성을 갖는 두 SSC를 레이저 도파로와 연결하고, 광결합 효율을 시뮬레이션 하였다. 큰 근접장 모드를 가지는 SSC는 낮은 광결합 효율을 보여주나, 원거리 발산각 패턴이 좁고 더 대칭적이다. 테이퍼 구조의 수동 도파로는 원거리 발산각 패턴을 열화시키지 않고 버트 조인트에서 도파로 오프셋의 무의존성과 광결합 효율을 향상시키기 위해 이용되었다. 이를 바탕으로 89.6%의 높은 광결합 효율과 16°×16°의 좁은 원거리장 발산각을 얻을 수 있었다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2005년도 추계종합학술대회
• /
• pp.627-630
• /
• 2005

Novel unified criterion to optimize power coupling at optical directional couplers with discontinuous input/output interfaces is first defined and evaluated numerically. The numerical results reveal that maximum power transfer between guiding slabs without discontinuous interfaces is dominated by conventional phase-matching condition while the guiding structures with discontinuous interfaces has maximum power transfer at an equi-partition condition, which describes the power distribution condition between two rigorous modes propagating through optical couplers.

• 전자공학회논문지D
• /
• 제35D권7호
• /
• pp.25-31
• /
• 1998

Modal transmission-line is utilized to analyze the power coupling of optical directional coupler composed by two parallel guiding slabs. By defining a coupling efficiency .eta. amenable to rigorous supermodes and boundary conditions of modal functions, we evaluate the power transfer for TE mode of gainy coupler. The results reveal that optimized power exchange occurs at a novel wavelength .lambda.$_{op}$ , which is generally different from minimum gap .lambda.$_{min}$ between rigorous modes and phase-matching condition .lambda.$_{ph}$ .

• 한국광학회지
• /
• 제20권2호
• /
• pp.128-133
• /
• 2009

본 연구에서는 광원을 내장하고 있는 포인팅 펜(pointing pen)의 출력광과 광 도파로 배열 사이의 광 결합을 이용하여 펜의 접촉여부와 접촉 위치를 검출하는 광학식 터치 패널 장치를 제안한다. 펜의 출력광과 광 도파로 배열 간의 광 결합을 최대화하고, 동시에 특정 광 도파로로 결합된 광속이 적은 손실로 전파할 수 있도록 하기 위해 광 도파로의 교차점 마다 부가적인 피라미드 구조를 삽입하였다. 광 도파로 단면의 크기가 $50{\times}50{\mu}m^2$인 경우 광선 추적법을 통해 결정된 피라미드의 최적 구조는 밑변의 폭, 높이, 경사각이 각각 $50{\mu}m$, $22.5{\mu}m$, $42^{\circ}$이었다. 이때 광 결합 효율은 97.8%이었으며, 전파손실은 평균적으로 0.3 dB/mm이었다. 그리고 펜의 기울어짐에 대한 허용 각도는 ${\pm}12^{\circ}$임을 확인하였다.