J. M. Oh

Electrically tunable slow and fast lights in a quantum-dot semiconductor optical amplifier near 1.55 μm

We have demonstrated both slow light in the absorption regime and fast light in the gain regime of a 1.55 microm quantum-dot semiconductor optical amplifier at room temperature. The theory with coherent population oscillations and four-wave mixing effects agrees well with the experimental results. We have observed a larger phase delay at the excited state than that at the ground state transition, likely due to the higher gain and smaller saturation power of the excited state.

Gain characteristics of InAs∕InGaAsP quantum dot semiconductor optical amplifiers at 1.5μm

The authors have fabricated ridge waveguide quantum dot (QD) semiconductor optical amplifiers (SOAs) on InP substrates that operate in the 1.5μm region. The active layer consists of InAs∕InGaAsP QD layers with a high dot density, but which still have good isolation between dots in the lateral and vertical directions, as confirmed by time-resolved photoluminescence measurements. One of these QD SOAs exhibited a fiber-to-fiber gain of 22.5dB and a chip gain of 37dB at 1.51μm. The spectral gain shape was found to be maintained for variations of the peak gain from 12to22dB, reflecting the zero-dimensional density of states at room temperature.

Simple and efficient L-band erbium-doped fiber amplifiers for WDM networks

Abstract The performance of L-band erbium-doped fiber amplifier (EDFA) of a simple structure with a fiber Bragg grating (FBG) was investigated. The injected C-band ASE by the FBG offers low-cost amplification and greatly improves the efficiency of the EDFA. There are 9 and 4 dB improvements with the FBG at 1587 nm, at low and high input, respectively. The flat gain of 18 dB, up to a total input of −5 dBm at 150 mW of 980 nm pump, is obtained over 30 nm with less than ±0.5 dB gain variations without any gain equalizer. The proposed EDFA provides a cost-effective solution for wavelength division multiplexing systems.

Incorporation of a fiber Bragg grating to improve the efficiency of a 1580-nm-band tunable fiber ring laser.

An efficient and tunable 1580-nm-band erbium-doped fiber ring laser is achieved by injection of amplified spontaneous emission in a conventional band by a fiber Bragg grating into the gain medium. The insertion of the fiber Bragg grating reduces the lasing threshold to 25%. The tuning range is 1560-1610 nm; the side-mode suppression ratio is better than 65 dB.

Strong tunable slow and fast lights using a gain-clamped semiconductor optical amplifier

Previously demonstrated slow light is still far from applications, particularly due to the limited bandwidth and control speed. Although semiconductor-based slow light has the high bandwidth and sub-nanosecond control speed, slow light was observed only in the absorption regime with attenuation, while fast light observed in the gain regime with amplification. The large power difference in two regimes makes the use of the optical delay impractical. We report novel slow light in the gain regime, with a high power comparable to that of fast light, utilizing the anomalous gain characteristic in a gain-clamped semiconductor optical amplifier. The slow light is tunable to fast light with the current as the only variable. Additional high speed operation, fast delay control, and wide range of operation wavelength make the present approach practical.

Demonstration of a low-cost flat-gain L-band erbium-doped fiber amplifier by incorporating a fiber Bragg grating

We have designed a very low cost, flat gain L-band EDFA, by employing a simple FBG and the bi-directional pumping scheme with only one uncooled 980 nm LD. The flat gain of 17 dB, up to the total output of 13(15.4) dBm at 97(150) mW of 980 nm pump, is obtained over 30 nm with less than +/- 0.5 dB gain variations. In addition, efficient and simple gain clamped L-band EDFA is demonstrated.

Slow and Fast Lights in a Quantum Dot Semiconductor Optical Amplifier near 1.55 μm

Slow light in the absorption regime and fast light in the gain regime are demonstrated in 1.55 μm quantum-dot semiconductor optical amplifiers at room temperature for both ground state and excited state.

Gain and high speed transmission characteristics of InAs/InP quantum dot Semiconductor Optical Amplifiers

High performance quantum dot semiconductor optical amplifiers with penalty free transmission of 10 Gb/s signal with gain of -8.2 dB and 40 Gb/s transmission with pattern-effect-free, wide open eye have been demonstrated.

Effective gain clamping of semiconductor optical amplifiers by injecting broad-band self-generated amplified spontaneous emission

A conventional SOA is effectively gain-clamped by the injection of self-generated broadband amplified spontaneous emission. The gain is clamped up to an input power of-2 dBm with an output power in excess of 11 dBm.

InAs/InGaAsP quantum dot semiconductor optical amplifiers at 1.5 μm: fabrication and gain characteristics

This paper reports on a InAs/InGaAsP quantum dot semiconductor optical amplifiers (SOAs) operating at 1.5 μm. An SOA exhibited a fiber-to- fiber gain of 22.5 dB and a chip gain of 37 dB while maintaining the spectral gain shape with current.