O. Parillaud

InP based lasers and optical amplifiers with wire-/dot-like active regions

Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire-/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 and 1.65 µm. In a brief overview different technological approaches will be discussed, while in the main part the current status and recent results of quantum-dash lasers are reported. This includes topics like dash formation and material growth, device performance of lasers and optical amplifiers, static and dynamic properties and fundamental material and device modelling. (Some figures in this article are in colour only in the electronic version)

Top grating index-coupled distributed feedback quantum cascade lasers

We report on the modeling and design of top grating distributed feedback (DFB) quantum cascade lasers (QCLs). A low loss, index-coupled, DFB design that is very robust against technological spreads is proposed. Strong DFB coupling conditions are obtained while maintaining a high laser output power. Following this design, DFB QCL lasers with InP cladding layers and InGaAs∕AlInAs active regions have been fabricated. Room temperature monomode QCLs with 30dB side mode suppression ratios are demonstrated over a 4–8μm wavelength range.

Room-temperature continuous-wave metal grating distributed feedback quantum cascade lasers

New design rules allow room temperature continuous wave operation Distributed Feedback Quantum Cascade Lasers using top metal gratings. Lasing between 4.5 and 7.5 µm and above 20 mW is achieved.

Optimization of an inductively coupled plasma etching process of GaInP∕GaAs based material for photonic band gap applications

In this article, we investigate the dry etching of GaInP∕GaAs based material system using an inductively coupled plasma (ICP) etching system. In a view to develop a suitable ICP process for the etching of aluminum-free material, ridge waveguides have been fabricated and the effects of the ICP parameters have been assessed. The coil power and the platen power have been varied at constant pressure and temperature for a chlorine-based process. The surface quality, sidewall profile, and selectivity have been reported. We also demonstrate the optimization of the chlorine-based process for deep etching and its subsequent implementation in photonic band gap device fabrication for 1.55μm optical applications. The optimized process has been shown to provide a high aspect ratio and a good selectivity for 250nm diam holes with a depth of 3μm in the GaInP∕GaAs material system. The influence of the ICP parameters on this material system have been analyzed mainly by scanning electron microscopy with particular attentio...

High-power room temperature emission quantum cascade lasers at /spl lambda/=9 /spl mu/m

We present two different techniques for processing InP-based /spl lambda/=9 /spl mu/m quantum cascade lasers which improve the thermal dissipation in the device. The first process is based on hydrogen implantation creating an insulating layer to inject current selectively in one part of the active region. The second process uses a thick electroplated gold layer on the laser ridge to efficiently remove the heat produced in the active region. Each process is designed to improve heat evacuation leading to higher performances of the lasers and will be compared to a standard ridge structure from the same wafer. We give evidence that the process of proton implantation, efficient in GaAs based structures, is not directly applicable to InP based devices and we present a detailed analysis of the thermal properties of devices with an electroplated gold thick layer. With these lasers, an average power of 174 mW at a duty cycle of 40% has been measured at 10/spl deg/C.

High-Power Tunable Dilute Mode DFB Laser With Low RIN and Narrow Linewidth

We have developed a 1-mm-long high-power DFB laser using an asymmetrical cladding based on the dilute waveguide technique. We have obtained about 180 mW output power at 25°C and >;30 mW at 15°C-85°C chip temperature with >;55-dB sidemode suppression ratio. This temperature range allows a 9.7-nm wavelength tunability. For high output power, the relative intensity noise is lower than -160 dB/Hz in the 0.08-40-GHz frequency range and the optical linewidth is better than 300 kHz.

Tunable high-finesse InP/air MOEMS filter

We have fabricated Fabry-Pe/spl acute/rot tunable filters based on a multi-air-gap/InP suspended structure. High spectral selectivity is achieved by displacing the resonant cavity into the high index material rather than in air. This configuration reduces the lateral losses of the cavity. The filters feature a bidirectional electrostatic actuation. A spectral linewidth better than 0.15 nm over a tuning range of 40 nm is experimentally demonstrated.

Gain, index variation, and linewidth-enhancement factor in 980-nm quantum-well and quantum-dot lasers

An experimental comparative study of the gain, index variation, and linewidth enhancement factor in 980-nm quantum-well (QW) and quantum-dot (QD) lasers structures, designed for high power applications, is presented. The gain spectra of the QW lasers at high injection level revealed three different transition energies, with a low linewidth enhancement factor (/spl sim/1.2) for E2HH2 transitions. Similar values for the linewidth enhancement factor, ranging between 2.5 and 4.5, were found for QW and QD devices, when comparing at similar values of the peak gain. This result is attributed to the contribution of excited state transitions in the measured QD lasers.

Substrate emitting index coupled quantum cascade lasers using biperiodic top metal grating

We report design of specific grating profile to perform substrate emission of metal grating Distributed Feedback Quantum Cascade Lasers. We achieve room temperature operation around 5.6 µm.

High-power and high-brightness laser diode structures using Al-free active region

High bit-rate, WDM, networks are reliant on Er or Er/Yb doped fiber amplifiers. Reliable, high power laser diodes at 980nm and 1480nm are key devices for pumping these amplifiers. We have developed several 980 nm laser diode structures at 980 nm, using an Aluminum free active region and standard AR/HR coatings on the facets. Our laser show low optical losses, low threshold current density and a high external differential efficiency. We demonstrate a mini-bar of small angle index guided tapered laser diodes (emissive width of 3 mm) with an optical output power of 20W at 33A under CW operation (25°C). The far field of the slow axis has a Gaussian single lobed shape, with a FWHM of 3.5° at maximum power, which is two times less than obtained with multimode broad area lasers. With such a device, we expect to couple 10W into a 100μm diameter fiber. We also demonstrate a large aperature gain-guided tapered laser with an output power of 2.4W and a calculated M21/c2 = 3, the M21/c2 factor being calculated with the method based on measurements of the fields profiles widths at 1/c2.