J. Landreau

Recent Advances on InAs/InP Quantum Dash Based Semiconductor Lasers and Optical Amplifiers Operating at 1.55

This paper summarizes recent advances on InAs/InP quantum dash (QD) materials for lasers and amplifiers, and QD device performance with particular interest in optical communication. We investigate both InAs/InP dashes in a barrier and dashes in a well (DWELL) heterostructures operating at 1.5 mum. These two types of QDs can provide high gain and low losses. Continuous-wave (CW) room-temperature lasing operation on ground state of cavity length as short as 200 mum has been achieved, demonstrating the high modal gain of the active core. A threshold current density as low as 110 A/cm2 per QD layer has been obtained for infinite-length DWELL laser. An optimized DWELL structure allows achieving of a T0 larger than 100 K for broad-area (BA) lasers, and of 80 K for single-transverse-mode lasers in the temperature range between 25degC and 85degC. Buried ridge stripe (BRS)-type single-mode distributed feedback (DFB) lasers are also demonstrated for the first time, exhibiting a side-mode suppression ratio (SMSR) as high as 45 dB. Such DFB lasers allow the first floor-free 10-Gb/s direct modulation for back-to-back and transmission over 16-km standard optical fiber. In addition, novel results are given on gain, noise, and four-wave mixing of QD-based semiconductor optical amplifiers. Furthermore, we demonstrate that QD Fabry-Perot (FP) lasers, owing to the small confinement factor and the three-dimensional (3-D) quantification of electronic energy levels, exhibit a beating linewidth as narrow as 15 kHz. Such an extremely narrow linewidth, compared to their QW or bulk counterparts, leads to the excellent phase noise and time-jitter characteristics when QD lasers are actively mode-locked. These advances constitute a new step toward the application of QD lasers and amplifiers to the field of optical fiber communications

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We demonstrate passive mode locking in one-section monolithic semiconductor laser diodes based on quantum-dash active layer at very high repetition rate in the 1.5μm window. Transform-limited pulses are generated at 134GHz with subpicosecond width, without any pulse compression scheme. A 50kHz linewidth of the radio-frequency spectrum is also demonstrated at 42GHz, the lowest value reported for any passively mode-locked semiconductor laser. We further show that the saturable absorption section in two-section devices has no significant impact on the mode-locking behavior.

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We propose a hybrid wavelength-division-multi-plexing/time-division-multiplexing architecture using reflective semiconductor optical amplifiers (RSOAs) for next-generation access solutions. We demonstrate that the use of a high gain and high output power RSOA as remote modulator enables a 36-dB optical budget for colorless operation at 2.5 Gb/s over 45-km single-mode fiber. This RSOA-based configuration provides a reasonable cost per user for this hybrid system and can be easily upgraded.

Subpicosecond pulse generation at 134GHz using a quantum-dash-based Fabry-Perot laser emitting at 1.56μm

This paper investigates the performance of a reflective semiconductor optical amplifier in a bidirectional wavelength-division multiplexed passive optical network at 2.5 and 5 Gbit/s over 20 and 15 dB link budget.

High Gain (30 dB) and High Saturation Power (11 dBm) RSOA Devices as Colorless ONU Sources in Long-Reach Hybrid WDM/TDM-PON Architecture

A vertical-access passive all-optical gate has been used to improve the extinction ratio of a 160 GHz picosecond pulse train at 1555 nm. An extinction ratio enhancement of 6 dB is observed within an 8 nm bandwidth. Such a device is a promising candidate for low-cost all optical reamplication and reshaping (2R) regeneration at 160 Gbits/s.

Demonstration of RSOA-based remote modulation at 2.5 and 5 Gbit/s for WDM PON

Several all-optical switching devices based on quantum well microcavity structures have been studied in view of their possible use for all-optical regeneration of telecommunication signals. Experiments and modeling show that the saturation energy is inversely proportional to a scaling factor describing the enhancement of the intracavity intensity at the Fabry-Perot resonance. As a result the saturation energy is approximately proportional to the number of quantum wells in the device and can be kept small by a proper cavity design.

All-optical extinction-ratio enhancement of a 160 GHz pulse train by a saturable-absorber vertical microcavity

We report a novel hybrid integrated optic device consisting of AlGaInAs/InP electroabsorption modulators and a four-arm silica-on-silicon planar lightwave circuit optical interferometer. The device is designed for generation of high spectral efficiency optical modulation formats. We demonstrate generation of 21.4 Gb/s quadrature phase shift keyed optical signals with electrical data drives of 2V(pp) amplitudes, achieving a bit error rate of 10(-9) with the required optical signal to noise ratio of ~18 dB in a 0.1 nm resolution bandwidth.

Scaling of the saturation energy in microcavity saturable absorber devices

By enhancing excitonic absorption in a new design of a polarization independent EA modulator, a 50 nm flat absorption spectrum, 42 GHz bandwidth devices together with 14-30 dB/V modulation sensitivity are obtained for 75 /spl mu/m long devices.

A hybrid electroabsorption modulator device for generation of high spectral-efficiency optical modulation formats

For high speed remote colorless modulation in FTTH technology, a new 10Gbit/s monolithically integrated amplified reflective electroabsorption modulator (R-EAM-SOA) is demonstrated over 50nm spectral range and over 20°C-60°C, with excellent eye diagrams.

42 GHz bandwidth InGaAlAs/InP electro absorption modulator with sub-volt modulation drive capability in a 50 nm spectral range

Measurements of SOA with various optical confinements show that low confinement devices are not saturated by ASE. This allows them to have good inversion factors at their input section, which leads to state-of-the-art noise factors.