Eun-Gu Lee

Demonstrations of RSOA based loop-back WDM-PON with 100 Gb/s (80 × 1.25 Gb/s) capacity employing spectrum sliced incoherent light injection

We have successfully demonstrated a loop-back WDM-PON with a 100 Gb/s (80×1.25 Gb/s) capacity using spectrally sliced ASE injected RSOA. To mitigate the RIN degradations, we proposed injection current adjustment, dispersion management and the use of receiver with optimized decision threshold level.

Improving transmission performance in EIN limited 2.5 Gb/s spectral slicing loop-back WDM-PON based on RSOA employing the dispersion management

We successfully demonstrated EIN-limited 2.5 Gb/s spectral slicing loop-back WDM-PON based on RSOA by using the dispersion management.

Compactly packaged monolithic four-wavelength VCSEL array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport

We report a cost-effective transmitter optical sub-assembly using a monolithic four-wavelength vertical-cavity surface-emitting laser (VCSEL) array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport using the data rate of common public radio interface option 6. The wavelength spacing is achieved using selectively etched cavity control layers and fine current adjustment. The differences in operating current and output power for maintaining the wavelength spacing of four VCSELs are <1.4 mA and <1 dB, respectively. Stable operation performance without mode hopping is observed, and error-free transmission under direct modulation is demonstrated over a 20-km single-mode fiber without any dispersion-compensation techniques.

Cost effective VCSEL array based 80-Gb/s TOSA for NG-PON2

The 8×10 Gb/s TOSA based on a VCSEL array was successfully developed for NG-PON2 application. For the cost effectiveness, direct optical coupling without lens array was used to package the TOSA. We have found that an optical and electrical crosstalk was small enough not to effect on a transmission performance.

Wavelength initialization technique for colorless gigabit WDM-PON

A new wavelength initialization technique is proposed for colorless gigabit wavelength division multiplexed-passive optical network (WDM-PON). It helps us reduce the time looking for the allocated channel independent of the number of channel of WDM-PON. This method is divided into two steps. First step is searching for wavelength band and second step is searching for a fine channel in wavelength band. The results of each step show that wavelength initialization time can be fixed independent on WDM-PON channels.

Wavelength-dependent characteristics of RSOA for color-free operations

We investigated the wavelength-dependent operating characteristics of RSOA with external injection for color-free operation over entire wavelength range of C-band or L-band, which can be widely applicable for RSOA-based WDM-PONs.

Modulation characteristics of AlAsGaAs double barrier quantum well resonant tunneling structure at microwave frequencies

Abstract We report the oscillation characteristics of a resonant tunneling diode oscillator (RTDO) in AlAs GaAs double barrier quantum well structure. Under the illumination of a Ti:Sapphire laser, the direct current-voltage curve shifts toward lower voltages. The oscillation frequency linearly decreases as the laser power increases at a constant bias voltage. These results suggest that the oscillation frequency of RTDOs can be controlled by the laser illumination.

Booting process technology for wavelength initialization in WDM-PON OLT and ONT

We propose a booting process related to a wavelength initialization of light source of optical line terminal (OLT) and optical network terminal (ONT) in wavelength division multiplexing passive optical network (WDM-PON). A stable operation of wavelength initialization is observed for OLT and ONT optical transceiver. The proposed process use minimized optical devices such as filter and photo diode (PD) for wavelength initialization.

APC receptacle type cooled RSOA-TOSA for WDM-PON transceiver

APC receptacle type cooled RSOA-TOSA with low return loss and high coupling efficiency was successfully developed for field-deployed WDM-PON application.

Switching characteristics of nonbiased optical bistability in asymmetric Fabry-Perot S-SEEDs made of extremely shallow quantum well structures

The asymmetric Fabry-Perot (AFP) cavity structure extremely shallow quantum wells (ESQWs) symmetric self-electro-optic effect device (S-SEED) shows nonbiased optical bistability. We analytically investigated the switching characteristics of the AFP ESQWs S-SEED (AE-SEED) using an impulse photocurrent response function and the corresponding voltage transients of the two p-i(ESQWs)-n diodes in AE-SEED. The result was compared to the characteristics of the conventional anti-reflection coated ESQWs S-SEED (E-SEED) with external bias. The large optical field and the thin intrinsic region in AE-SEED reduce the required incident switching energy and operating voltage, respectively. According to our analysis, the switching energy of an impedance-matched AE-SEED is 1.2 fJ μm -2 , while that of an E-SEED is 4.1 fJ μm -2 . With a reasonable RC time constant and device size, the switching time of the AE-SEED is 11 ps while that of E-SEED is 12.4 ps for the minimum switching energy of each device.