Seung Il Myong

Loop-back WDM-PON with 100 Gb/s capacity using spectrally sliced ASE injected RSOA

We experimentally investigated the 1.25 Gb/s operation of a spectrally sliced amplified spontaneous emission (ASE) injected reflective semiconductor optical amplifier (RSOA) with 50 GHz channel spacing using an injection current adjustment, dispersion management, and the use of an optical receiver with an optimized decision threshold level. We mitigated the relative intensity noise (RIN) degradation caused by post-filtering through the injection current adjustment, and also alleviated the dispersion-induced RIN degradation with the help of the dispersion management method. Finally, the use of an optical receiver with an optimized decision threshold level eliminated error floors, which were attributed to an unequal noise distribution between the mark level and the space level. We also successfully demonstrated a loop-back wavelength division multiplexing-passive optical network (WDM-PON) with a 100 Gb/s (80 × 1.25 Gb/s) capacity using a spectrally sliced ASE injected RSOA by means of the three aforementioned methods. We also analyzed and examined the transmission impairments, such as the dispersion penalty and back-reflection induced penalty, in a 1.25 Gb/s bidirectional WDM-PON based on an RSOA with 50 GHz channel spacing.

Identification method of non-reflective faults based on index distribution of optical fibers.

This paper investigates an identification method of non-reflective faults based on index distribution of optical fibers. The method identifies not only reflective faults but also non-reflective faults caused by tilted fiber-cut, lateral connector-misalignment, fiber-bend, and temperature variation. We analyze the reason why wavelength dependence of the fiber-bend is opposite to that of the lateral connector-misalignment, and the effect of loss due to temperature variation on OTDR waveforms through simulation and experimental results. This method can be realized by only upgrade of fault-analysis software without the hardware change, it is, therefore, competitive and cost-effective in passive optical networks.

Investigations of upstream transmission performances with cost-effective transmitter front-end for ONU in IM/DD OFDMA-PON

We propose an OFDM transmitter with simple and low cost front-end for uplink configurations in IM/DD OFDMA-PON. The upstream transmission performances were numerically investigated to obtain relatively better symbol error rate by varying frequency spacing between adjacent LO, optical carrier frequency detuning under various QAM mapping methods.

Experimental investigations of RIN of spectrally sliced ASE injected RSOA in WDM-PON for mobile fronthauling applications based on CPRI line rate option 3

We experimentally investigated the various operating conditions of RSOA in the wavelength seeded WDM-PON using spectrally sliced ASE injected RSOA for mobile fronthauling applications based on CPRI line rate option 3.

CPRI transceiver for mobile front-haul based on wavelength division multiplexing

This paper describes the necessity of the optical transceivers for the mobile fronthaul based on wavelength division multiplexing (WDM). Among various candidates, we have proposed an external cavity laser (ECL) based on inexpensive thin film filter. Transmission over single mode fiber of 20 km is examined under direct modulation of common public radio interface (CPRI) line rate option 3.

Design and implementation of correlation-based optical time-domain reflectometer transceiver

Design and implementation of a correlation-based OTDR (C-OTDR) transceiver is discussed. The C-OTDR uses a high-power low noise avalanche photo diode detector and transimpedance and variable gain amplifiers with correlation-based OTDR FPGA modem. A dynamic range of approximately 38 dB is demonstrated. Spatial resolution of 5 meter and event dead zone of 10 meter are achieved.

Analysis on causes of faults and OTDR waveforms for optical link management

This paper has analyzed reflection types and index distribution in optical links and the consequent OTDR waveforms for various causes of link faults. For the advanced fault identification, the changes of index distribution by fibers bend have been simulated by the conformal transformation method. Faults due to the connectors misalignment originate from coupling loss; however, faults by the bend originate from tilted index distribution. The wavelength dependence of loss by the misalignment is directly opposite to that by the bend. Using the properties of the index distribution and wavelength dependence, the causes for the smooth decrease on OTDR trace could be identified exactly.

Fault-identification method based on index distribution of optical fibers for enhanced optical link monitoring

This paper has investigated the enhanced fault-identification method based on the difference of intrinsic properties within an optical fiber. We have verified a fault-identification method using the wavelength dependency of non-reflective events through the experiment.