Structural & Spectroscopic Study of InAs/InP Quantum Dots for Dual-Frequency Laser Engineering

(1)

Institut Foton, UMR 6082

CNRS, Université de Rennes 1, INSA Rennes Rennes, Lannion - France

JNMO

2018

Structural & Spectroscopic Study of

InAs/InP

Quantum

Dots

for

Dual-Frequency Laser Engineering

Introduction

Conclusion

Spectral Hole Burning

Requirements for the QDs

Photoluminescence Spectral Hole Burning

Density

Telecom

wavelength

Homogeneous linewidth Atomic Force Microscopy

Tuning of the QDs density - AFM

λ_{𝑝𝑢𝑚𝑝}

The pump laser saturates the absorption spectrum of an inhomogeneous medium

InAs/InP QDs

Molecular Beam Epitaxy Growth parameters:

• AsH₃ Flow

• Quantity of deposited InAs

Weak Coupling

 QDs density (and coupling) mainly controlled by the As flow: changed from 𝟏𝟎𝟏𝟏 down to

𝟏𝟎𝟏𝟎_𝒄𝒎−𝟐_{, with a strong effect on the wavelength emission: from 1500 nm to 1945 nm}

 Independent control of the density and wavelength (double cap)

 _{SHB experimental setup ready with good resolution (<0.5nm) and high spectral range (500 nm)}

 Results on QWs correspond well with the bibliography

The homogeneous linewidth

𝜸 = 𝜞_𝒉𝒃/2

Problem

Few efficient compact tunable

room temperature THz sources

available

0 2 4 6 8 10 12 14 2,0x1010 4,0x1010 6,0x1010 8,0x1010 1,0x1011 1,2x1011 1,4x1011 den si ty (/c m²) AsH3 (cc) 1ML 1,5ML 2ML

2,5ML QDs density as a function of AsH₃ Flow

Preliminary Results (on QWs)

J. S. Weiner et al., “Nonlinear spectroscopy of InGaAs/InAlAs multiple quantum well structures”, Applied Physics Letters,1986

Perspectives

 _{Achievement of SHB in order to get the homogeneous linewidth}

broadening as a function of QDs density, temperature, input power

 _{Optimisation of QDs density to get the weaker coupling}

 VECSEL characterisation

Control of the wavelength – Double Cap

Emission Wavelength for different AsH₃ flow

QDs Wavelength: Tendency with growth parameters but impossibility

to control it by only the growth

Double cap process

AFM images (1x1 μm²) of the InAs/InP Quantum Dots which have different growth parameters

Experimental Setup

Experimental SHB spectrum and Reference

Same shape, good resolution (visible interferences due to the sample), higher spectral range Typical characteristics of QWs: thermal carriers exponential decline, exciton photo-bleaching

Spatial Light Modulator screen

Wavelength beating from a Coherent dual wavelength Quantum Dots (QDs) based Vertical External Cavity Surface Emitting

Laser (VECSEL)

Why VECSEL ?

o Low intensity and phase noise

o Dual-wavelength regime possible

Why QDs ?

o Weak coupling (inhomogeneous medium) o Possible electrical injection

G. Brévalle

1

_{, M. Perrin}

1

_{, C. Paranthoën}

1

_{, C. Levallois}

1

_{, Y. Léger}

1

_{, H. Folliot}

1

_{, M. Alouini}

1

_{Univ Rennes, INSA Rennes, CNRS, Institut FOTON – UMR 6082, F-35000 Rennes, France}

gaelle.brevalle@insa-rennes.fr

This research project is supported by the

IDYLIC ANR project

QDs size and emission wavelength

The radius of the QDs is bigger for higher flow

QDs = self-assembled nanostructure  impossible to control the size and consequently the wavelength

For 2ML: QDs radius and wavelength as a function of As Flow Bigger QDs  Higher emission wavelength

When the AsH₃ Flow increases, the QDs get bigger and the density greatly

decreases (x10)

Schematic of the Double cap process