Ayako Murakami

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

We investigate the effects of the discrete reflection on the performances of upstream and downstream signals in the wavelength-division-multiplexed passive optical network (WDM PON) implemented in a single-fiber loopback configuration using the reflective semiconductor optical amplifiers (RSOAs). We first analyze the optical beat interference (OBI) noise caused by the discrete reflection, and clarify the relation between the reflection tolerance and the networks operating conditions such as the RSOA gain, the link loss, and the location of the reflection point, etc. The results show that the impact of the reflection can be expressed by using the effective crosstalk level. We then measured the reflection tolerance of the RSOA-based WDM PON, in which the downstream signal operating at 1.25 Gb/s is remodulated by the RSOA at the subscribers site for the transmission of 155-Mb/s upstream signal. The reflection tolerances are measured to be in the range of -42 to - 35 dB for the downstream signals and -29 to -19 dB for the upstream signals, depending on the RSOA gain. These small reflection tolerances are caused by the fact that the reflected light is re-amplified by the RSOA. We also show that the dependence of the reflection tolerance on the RSOA gain can be explained by using the effective crosstalk level. These results are used to evaluate the impacts of the unwanted discrete reflections on the RSOA-based WDM PON.

Demonstration of RSOA-based WDM PON Operating at Symmetric Rate of 1.25 Gb/s with High Reflection Tolerance

We demonstrate an RSOA-based WDM PON operating at the symmetric rate of 1.25 Gb/s by using a low-frequency subcarrier (2.5 GHz). The performance is robust against the remodulation noise as well as the reflection noise.

Recent progresses in RSOA-based WDM PON

We report on the recent progresses in the wavelength-division-multiplexed passive optical network (WDM PON) based on the reflective semiconductor amplifiers (RSOAs), including the enhanced operable temperature range, effects of reflection and its mitigation methods, 10 Gb/s operation by using electronic equalizers and forward error-correction (FEC) codes, and increased maximum reach to ≫100 km by using a novel self-homodyne receiver.

Power managed optical point-to-multipoint (P2MP) tree signalling demonstration in GMPLS-controlled wavelength switched optical networks

Dynamic control to graft and prune optical point-to-multipoint trees was successfully demonstrated in a WSON testbed by utilizing GMPLS signaling extensions. By using wavelength selective switch with variable optical power split function, a power managed P2MP tree could be constructed.

Reflection tolerance enhancement of RSOA-based WDM PON by using optical frequency dithering

We investigate the effectiveness of optical frequency dithering to enhance the reflection tolerance of RSOA-based WDM PONs. We show that the reflection-induced penalty can be substantially reduced in both directions by the same dithering frequency.

Digital terrestrial broadcasting transport system in SDH network

We have developed a digital terrestrial broadcasting transport system to realize the broadcast infrastructure based on a SDH network, and confirmed a high accurate frequency transmission of OFDM sample clock in a SDH network.

Study of a Raman Crosstalk Management Technique for Analog Video RF Signal Transmission Systems

When analog terrestrial broadcasting and Gigabit Ethernet signals co-exist in the same network, the Raman crosstalk effect might damage the analog video signal. In this paper, we have investigated the effectiveness of adding some dispersion at the input-end of the fiber to manage the Raman crosstalk and successfully demonstrated adequate suppression of the interference on the analog video signal

Analysis on SRS-Induced Performance Impairment of Downstream Data Signal in Video Overlay EPON Systems

Impacts of Raman crosstalk on downstream data signal in video overlay EPON systems were studied. The crosstalk-induced power penalty was found less than 0.1dB (average) when video signal power is 18dBm or lower with ≪10% OMI.

Study of performance-monitoring method using asynchronous codedetermination

Feature Issue on Optical Performance Monitoring (OPM). A method for asynchronous code determination (ACD) is one of the most promising ways of monitoring signal quality in transparent networks, since it does not require any clock recovery circuits. In the case of the conventional ACD scheme using the asynchronously measured probability-density function (PDF) of the inside of an eye-diagram, the PDF often becomes distant from Gaussian distribution, owing to cross points of the received signal eye-diagram, which is undesired. In contrast, when we use the asynchronously measured PDF of the outside of the eye-diagram, the above-mentioned PDF distortion problem is by nature lessened, and this is useful for stable monitoring of signal quality. We report the results of the performance-monitoring scheme, using the asynchronously measured PDF of the outside of an eye-diagram.