• Journal of the Optical Society of Korea
• /
• 제8권1호
• /
• pp.29-33
• /
• 2004

We propose and demonstrate a novel optical pulse multiplier applicable to OTDM (Optical Time Division Multiplexing) systems using cascaded long-period fiber gratings. We have exploited the fact that each mode in a fiber has a different propagation constant to obtain time delays among optical pulses. The proposed scheme could realize high-frequency optical pulse multiplication for optical short pulse trains. We have successfully implemented two, four, and eight times multiplications with the maximum repetition rate of 416.7 ㎓. The obtained pulse delays are well matched with the simulated ones.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
• /
• pp.236-237
• /
• 2004

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

• 한국재료학회지
• /
• 제12권4호
• /
• pp.254-258
• /
• 2002

To realize channel cross-connecting in optical communications systems, a high speed optical matrix switch was fabricated using z-cut $LiNbO_3$. For switch fabrication was design bending structure and coupling length and four $2{\times}2$ directional couplers were integrated on one substrate far construction of a $4{\times}4$ switch. Single-mode optical waveguides were formed by Ti-diffusion at a wet $O_2$ atmosphere. Ti-diffusion profile, refractive index variation and waveguide morphology were analyzed by Prism coupler and optical microscopy, respectively.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2007년도 하계학술발표회 논문집
• /
• pp.213-214
• /
• 2007

• Journal of the Optical Society of Korea
• /
• 제9권2호
• /
• pp.54-58
• /
• 2005

A novel mode analysis method and differential mode delay measurement technique for a multimode optical fiber based on optical frequency domain reflectometry has been proposed for the first time. We have used a conventional OFDR with a tunable external cavity laser and a Michelson interferometer. A few-mode optical multimode fiber was prepared to test our proposed measurement technique. The differential mode delay (DMD) of the sample fiber was measured to be 16.58 ps/m with a resolution of 1.5 ps/m. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 G
• /
• pp.2492-2494
• /
• 1998

Recently the optical fiber lines have been widely deployed in the trunk lines and digital data service network. The unexpected failures of optical fiber lines by natural disasters and road construction work have increased rear by rear and the number of damaged telecommunication lines per failures is on increasing. In the meantime, it takes long time to recover the optical fiber lines failures. So, it is important to maintain and monitor the status of optical fiber lines for prevention of optical fiber lines failures. Therefore, KT(Korea Telecom) needs efficient and automatic maintenance system to operate and monitor the optical fiber lines. FLOMS(Fiber Line Operation and Monitor System) had been developed in '96 and pilot system was installed at telephone offices in '97. This paper describes the FLOMS which carries out the functions of efficient maintenance and supports for monitoring optical fiber lines and managing facilities in optical fiber lines.

• Current Optics and Photonics
• /
• 제4권4호
• /
• pp.267-272
• /
• 2020

The propagation of a truncated Airy beam with spatial phase modulation (SPM) is investigated in Kerr nonlinearity with an optical lattice. Before the truncated Airy beam enters the optical lattice, a sinusoidal phase is introduced on the wave-front of the beam. The effect of the spatial phase modulation and optical lattice on propagation behavior is analyzed by direct numerical simulation. It is found that the propagation direction of a truncated Airy beam can be effectively controlled by adjusting the values of phase shift. The effects of optical amplitude, truncation factor, spatial modulation frequency, lattice period and lattice depth on the propagation are discussed in detail. By choosing a high modulation depth, the finite-energy Airy beam can be deflected with a large deflection angle in an optical lattice.

• Current Optics and Photonics
• /
• 제4권4호
• /
• pp.310-316
• /
• 2020

We propose and experimentally demonstrate an all-optical radio frequency (RF) spectrum broadening system based on time compression. By utilizing the procedure of dispersion compensation values, the frequency domain is broadened by compressing the linear chirp optical pulse which has been multiplexed by the radio frequency. A detailed mathematical description elucidates that the time compression is a very preferred scheme for spectrum broadening. We also report experimental results to prove this method, magnification factor at 2.7, 8 and 11 have been tested with different dispersion values of fiber, the experimental results agree well with the theoretical results. The proposed system is flexible and the magnification factor is determined by the dispersion values, the proposed scheme is a linear system. In addition, the influence of key parameters, for instance optical bandwidth and the sideband suppression ratio (SSR), are discussed. Magnification factor 11 of the proposed system is demonstrated.

• 한국광학회지
• /
• 제14권5호
• /
• pp.530-534
• /
• 2003

새로운 전광(all-optical) NOR논리소자가 반도체 광증폭기 (SOA)의 이득포화 특성을 이용하여 처음으로 제안되고 입증되었다. 전광 NOR논리소자는 이득의 비선형성에 의해 동작되므로 SOA의 이득포화를 충분히 얻기 위해 펌프신호는 SOA의 입력단에서 어븀 첨가 광섬유 증폭기에 의해 증폭되었다. 전광 NOR 논리소자의 동작특성은 10 Gbit/s에서 성공적으로 측정되었다.