Effects of Reflection in RSOA-Based WDM PON Utilizing Remodulation Technique

Recent progresses in RSOA-based WDM PON

“…We then measure the reflection tolerance of the RSOA-based WDM PON, in which the downstream signal operating at 1.25 Gb/s is re-modulated by the RSOA at the subscriber's site for the transmission of 155 Mb/s upstream signal. The reflection tolerances are measured to be in the range of -42 dB ~ -35 dB for the downstream signals and -29 dB ~ -19 dB for the upstream signals, depending on the RSOA gain [10]. These small reflection tolerances are caused by the fact that the reflected light is re-amplified by the RSOA.…”

“…In spite of this optimization, however, the effect of the reflected upstream light on the downstream receiver can still be severe. Thus, it may be unavoidable to utilize a mitigation technique of the discrete reflections for the practical development of the RSOA-based WDM PON [10]. To mitigate the effects of the reflection, we have either increased the orthogonality between the upstream and downstream signals (by using the Manchester coding or sub-carrier multiplexing), or used the seed light with a broad optical spectrum (by using the ASE source as the seed light or dithering the downstream signal used as the seed light) [11]- [15].…”

The Optical Filtering Effect of a RSOA-based Broadband Light Source in a Bidirectional WDM-PON System

“…따라서, RSOA는 ONU의 광신호 발생 장치 의 비용을 경감하기 위한 방법으로 크게 주목을 받고 있다 [9] . 하지만 ONU에서 사용될 때 파장 의존성에 영향을 받지 않고 반도체 부품의 특성상 다른 부품들과 결합이 용이하다 는 장점 등에도 불구하고, 산란되거나 반사된 광세기에 의한 신호 악화나 광 필터에 대한 의존성 등과 같은 해결되어야 할 몇 가지 단점을 가지고 있는 것도 사실이다 [10,11] . 이 필터 효과는 우리 연구 그룹에 의해 부분적으로는 측정된 바 있지 만 이 실험은 필터의 하드웨어 특성을 쉽게 바꿀 수 없어서 제한적인 결과만 도출이 되었다 [12] .…”

A Bidirectional Directly Modulated Cable Pon Based on a Rsoa

“…In recent studies, reflective semiconductor optical amplifier (RSOA) has been used as wavelength reuse and remodulation schemes in bidirectional wavelength-division-multiplexing PON and radio-over-fiber transport systems [5,6]. But, its application in a bidirectional directly modulated cable PON has not been reported.…”