Hoon-Keun Lee

A WDM-PON with a 40 Gb/s (32 x 1.25 Gb/s) capacity based on wavelength-locked Fabry-Perot laser diodes.

We investigate a high capacity WDM-PON based on wavelength locked Fabry-Perot laser diodes. An error-free transmission of 1.25 Gb/s per subscriber was achieved with a flat-top passband AWG and a laser diode with low reflectivity. Then, we demonstrate a WDM-PON of 40-Gb/s capacity of 32 channels over 15 km of single mode fiber. It also shows that color-free operation within conventional C-band wavelength. The observed dispersion penalty after 30 km transmission was 0.5 dB. The demonstrated WDM-PON shows a robust transmission performance on the optical back reflection.

All-optical clock recovery from NRZ data of 10 Gb/s

We demonstrate successfully an all optical clock recovery scheme based on all-fiber devices from nonreturn-to-zero format data of 10 Gb/s with a stabilized asymmetric Mach-Zehnder interferometer and a mode-locked erbium-doped fiber laser. This all-optical clock recovery method will find application in ultrahigh-speed all-optical communication systems.

A WDM-PON with an 80 Gb/s capacity based on wavelength-locked Fabry-Perot laser diode

We investigate a high capacity WDM-PON based on wavelength-locked Fabry-Perot laser diodes. A color-free transmission of 2.5 Gb/s per channel is achieved with a polarization independent F-P LD and a decision threshold control circuit at the receiver. Then, we demonstrate an 80 Gb/s capacity (2.5 Gb/s x 32 channels) WDM-PON with transmission length of 20 km. We also investigate impairments in transmission.

Decision Threshold Control Method for the Optical Receiver of a WDM-PON

We demonstrate an improvement of optical receiver performance for an optical signal with beat noises. The decision threshold level is adjusted automatically according to the detected average optical power. This simple method improves optical receiver performance under a wide range of input signal conditions, e.g., beat noise level and extinction ratio. Thus this proposed method is useful to optical receivers for WDM-PONs. By employing this control circuit, we successfully demonstrate a WDM-PON based on a wavelength-locked Fabry–Perot laser diode at 1.25 Gb/s per channel with 100 GHz spacing.

Self-Restorable WDM-PON With a Color-Free Optical Source

We propose and demonstrate a self-restorable wavelength-division-multiplexing passive optical network (WDM-PON) with a color-free optical source. When the distribution and feeder fiber links are broken, we can successfully recover the network by using optical switches and/or Ethernet switches. If the fault monitors detect the failures, optical switches change the transmission path and the failures are recovered within 10 ms. If we use only Ethernet switches, we can also protect the transmission path failure with the help of the link aggregation control protocol.

A Simple and Color-Free WDM-Passive Optical Network Using Spectrum-Sliced Fabry–PÉrot Laser Diodes

We propose and demonstrate a simple and color-free wavelength-division-multiplexing passive optical network (WDM-PON) using spectrum-sliced Fabry-Perot laser diodes (F-P LDs). Due to its low front facet reflectivity (~0.1%), the F-P LD shows a broadband lasing spectrum and reduced mode partition noise. By utilizing multiple peaks that are separated by the free-spectral range of the cyclic arrayed waveguide gratings, the 16-channel WDM-PON is successfully demonstrated at 155 Mb/s.

Automatic wavelength allocation method using Rayleigh backscattering for a WDM-PON with tunable lasers

We propose an automatic wavelength control method using Rayleigh backscattering in a feeder fiber for tunable lasers employed in a wavelength-division multiplexing passive optical network. We demonstrate two realization methods, maximizing backscattered power and maximizing the second harmonic component with wavelength modulation. We analyze their limiting factors and impacts on the system performance. We use a VCSEL as a low-cost tunable light source.

A WDM-PON with a 40 Gb/s capacity based on wavelength-locked Fabry-Perot laser diodes

We demonstrate a 40 Gb/s capacity (1.25 Gb/s times 32 channel) WDM-PON based on wavelength locked Fabry-Perot laser diodes with a high immunity to the optical back reflection.

A Seamless Evolution Method With Protection Capability for Next-Generation Access Networks

We propose and demonstrate a seamless evolution method with protection capability for next-generation (NG) access networks. Both a time-division-multiplexing passive optical network (TDM-PON) and a wavelength-division-multiplexing (WDM-PON) can be accommodated in the same fiber infrastructure and failures of feeder fibers and distribution fibers are protected for each service. Remote reconfigurations of the remote node (RN) for protection and/or evolution can be achieved within 48 ms by instantaneous optical powering at the central office (CO) while maintaining the RN in a passive state.

Automatic wavelength control method using Rayleigh backscattering for WDM-PON with tunable lasers

We demonstrate an automatic wavelength control method using Rayleigh backscattering and wavelength modulation for tunable lasers in a WDM-PON. By measuring the spectrum of backscattered light, we identified and tracked the allocated wavelength.