• Korean Journal of Optics and Photonics
• /
• v.14 no.2
• /
• pp.146-149
• /
• 2003

Nanosecond pulses are efficiently amplified by a two-stage EDFA. The EDFA employs an optical bandpass filter between stages to remove the amplified spontaneous emission of the first EDFA that strongly saturates the gain of the second EDFA. The peak power of the amplified output pulse is 83 W when that of the input pulse of 10 ㎱width and 100 $mutextrm{s}$ period is 1 ㎽.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.142-143
• /
• 2003

EDFA의 이득(gain)과 잡음지수(noise figure)는 매우 중요한 특성 중의 하나이다. 전송 시스템에서 필연적으로 발생하는 ASE 잡음을 제거하는 것이 중요하다. EDFA의 중간에 필터(filter)와 아이솔레이터(isolator)를 삽입하여 불필요한 ASE를 제거함으로써 이득과 잡음지수를 향상시킬 수 있으며, 기존의 단일경로(single-pass) EDFA에서 필터의 위치가 40-60％ 근처에서 이득과 잡음지수 향상이 가장 크게 된다. 그러나, 거울(mirror)을 사용하여 증폭 효율을 높인 이중경로(double-pass) EDFA에서 필터에 의한 이득 향상에 관한 연구발표는 아직까지 없다. (중략)

• Journal of the Optical Society of Korea
• /
• v.7 no.2
• /
• pp.64-66
• /
• 2003

The optical gain and noise figure improved double-pass two-stage EDFA using a mirror, circulator, and gain-flattening filters is proposed. By double passing the pump light and removing the ASE propagating into the input part, the signal gain of 5 ㏈ and noise figure of 2.1 ㏈ are improved compared to the conventional single- and double-pass EDFA With gain-fattening filters in the second stage of EDFA, we obtain an improved flat gain with a gain flatness less than 1 ㏈ over 33-nm wavelength range at the 980-nm pump power of 86 ㎽.

• Journal of the Optical Society of Korea
• /
• v.4 no.1
• /
• pp.14-18
• /
• 2000

We have investigated gain flattening of EDFA systems with or without a gain equalizer for WDM long-haul transmission using a re-circulating EDFA loop. Without a gain equalizer, gain variation as small as 2.9 dB was achieved over the 10-nm band of a 100 cascaded EDFA system by the inversion principle. With a gain equalizer based on all-fiber acousto-optic tunable filters, two different config-urations of EDFAs were tested. For a single-stage EDFA scheme, the 21-nm band has shown 3.8 dB of gain variation at 17.4 ∼ 20.3 dB of OSNRs after the 100the stage of EDFAs. For a dual-stage EDFA scheme, a wider bandwidth of 34 nm has shown 3.6-dB variation after 40 cascaded EDFAs.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.140-141
• /
• 2003

광섬유 통신에서 넓은 대역폭 증폭을 이루기 위하여 광대역 증폭기가 필요하다. 증폭기의 대역폭을 넓히기 위해 C-대역과 L-대역 EDFA를 결합하여 사용하는 등의 여러 가지 방법이 제안되고 있다. 그 중 L-대역을 결합하는 방법이 실제 시스템 적용에서 가장 즉시 이용가능한 방법이라 할 수 있다. L-대역 EDFA의 경우 상대적으로 이득이 낮으며 효율이 떨어진다. 이득이나 효율을 높이기 위해서 FBG, 양방향 펌핑(bidirectional pump), 그리고 이중경로(double-pass) 구조를 이용하는 방법이 제안되었다. (중략)

• Journal of the Optical Society of Korea
• /
• v.11 no.1
• /
• pp.44-48
• /
• 2007

A two-stage gain-clamped erbium doped fiber amplifier (GC-EDFA) using a pump laser diode and a 16 channel wavelength division multiplexing (WDM) with 0.8 nm spacing in C band of $1,545{\sim}1,560nm$ wavelength is experimentally demonstrated for a burst packet mode optical switching system.

• Korean Journal of Optics and Photonics
• /
• v.14 no.2
• /
• pp.189-193
• /
• 2003

A two-stage erbium-doped fiber amplifier (EDFA) with a band pass filter is used to get optical pulses of high peak value. The pulse signal has a 32 ㏈ extinction ratio, 125 W peak power and 79 ㎽ pulse off power. A nonlinear optical loop mirror (NOLM) is used to lower the pulse off power so as to increase the extinction ratio. The pulse signal after the NOLM has a 50.4 ㏈ extinction ratio, 35 W peak power and 0.3 ㎽ pulse off power.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.11
• /
• pp.1666-1671
• /
• 2022

The structure of a high-power gain-flattened long wavelength band (L-band) optical amplifier was optimized, which was implemented for 64-channel wavelength division multiplexed optical signals with a channel spacing of 50 GHz. The output characteristics of this L-band amplifier were measured and analyzed. The amplifier of the optimized two-stage amplification configuration had a flattened gain of 20 dB within 1 dB deviation between 1570 and 1600 nm for -2 dBm input power condition. The noise figure under this condition was minimized to within 6 dB in the amplification bandwidth. The gain flattening was realized by considering only the characteristics of gain medium in the amplifier without using additional optical or electrical devices. The proposed amplifier consisted of two stages of amplification stages, each of which was based on the erbium-doped fiber amplifier (EDFA) structure. The erbium-doped fiber length and pumping structures in each stage of the amplifier were optimized through experiments.