This paper aims to investigate the effects of the temperature on the mode-locking capability of two section InAs/InP
quantum nanostructure (QN) passively mode locked lasers. Devices are made with multi-layers of self-assembled InAs
QN either grown on InP(100) (5 quantum dashes (QDashes) layers) or on InP (311)B (6 quantum dots (QDs) layers).
Using an analytical model, the mode-locking stability map is extracted for the two types of QN as a function of optical
absorption, cavity length, current density and temperature. We believe that this study is of first importance since it
reports for the first time a systematic investigation of the temperature-dependence on the mode-locking properties of
InAs/InP QN devices. Beside, a rigorous comparison between QDashes and QDs temperature dependence is proposed
through a proper analysis of the mode-locking stability maps. Experimental results also show that under some specific
conditions the mode-locking operation can be temperature independent.
Lattice-matched GaP-based nanostructures grown on silicon substrates is a highly rewarded route for coherent
integration of photonics and high-efficiency photovoltaic devices onto silicon substrates. We report on the structural and
optical properties of selected MBE-grown nanostructures on both GaP substrates and GaP/Si pseudo-substrates. As a
first stumbling block, the GaP/Si interface growth has been optimised thanks to a complementary set of thorough
structural analyses. Photoluminescence and time-resolved photoluminescence studies of self-assembled (In,Ga)As
quantum dots grown on GaP substrate demonstrate a proximity of two different types of optical transitions interpreted as
a competition between conduction band states in X and Γ valleys. Structural properties and optical studies of
GaAsP(N)/GaP(N) quantum wells coherently grown on GaP substrates and GaP/Si pseudo substrates are reported. Our
results are found to be suitable for light emission applications in the datacom segment. Then, possible routes are drawn
for larger wavelengths applications, in order to address the chip-to-chip and within-a-chip optical interconnects and the
optical telecom segments. Finally, results on GaAsPN/GaP heterostructures and diodes, suitable for PV applications are
reported.
This paper reports the fabrication and the characterisation of a 10 GHz two-section passively mode-locked quantum dash
laser emitting at 1.59 μm. The potential of the device's mode-locking is investigated through an analytical model taking
into account both the material parameters and the laser geometry. Results show that the combination of a small absorbing
section coupled to a high absorption coefficient can lead to an efficient mode-locking. Characterisation shows mode-locking
operation though output pulses are found to be strongly chirped. Noise measurements demonstrate that the single
side band phase noise does not exceed -80 dBc/Hz at 100 kHz offset leading to an average timing jitter as low as 800 fs.
As compared to single QW lasers these results constitute a significant improvement and are of first importance for
applications in optical telecommunications.
Thanks to optimized growth techniques, a high density of uniformly sized InAs quantum dots (QD) can be grown on
InP(113)B substrates. Low threshold currents obtained at 1.54 μm for broad area lasers are promising for the future. This
paper is a review of the recent progress toward the understanding of electronic properties, carrier dynamics and device
modelling in this system, taking into account materials and nanostructures properties. A first complete analysis of the
carrier dynamics is done by combining time-resolved photoluminescence experiments and a dynamic three-level model,
for the QD ground state (GS), the QD excited state (ES) and the wetting layer/barrier (WL). Auger coefficients for the
intradot assisted relaxation are determined. GS saturation is also introduced. The observed double laser emission for a
particular cavity length is explained by adding photon populations in the cavity with ES and GS resonant energies. Direct
carrier injection from the WL to the GS related to the weak carrier confinement in the QD is evidenced. In a final step,
this model is extended to QD GS and ES inhomogeneous broadening by adding multipopulation rate equations
(MPREM). The model is now able to reproduce the spectral behavior in InAs-InP QD lasers. The almost continuous
transition from the GS to the ES as a function of cavity length is then attributed to the large QD GS inhomogeneous
broadening comparable to the GS-ES lasing energy difference. Gain compression and Auger effects on the GS transition
are also be discussed.
InAs nanostructures formed on InP substrates allow the realization of devices working in telecommunication wavelength range between 1.4 and 1.65 μm. However due to the low lattice mismatch existing between InAs and InP, the self assembling process in InP is more complex than on GaAs substrates. First high density quantum wires obtained on InP(001) have been integrated in laser. Lasers emitting at room
temperature have been achieved. For an infinite length cavity, a threshold current density per QD plane as low as 45 A/cm2 is deduced. This result compares favourably with those obtained on quantum wells lasers. However, the stability of the threshold current with temperature, predicted for quantum dots laser is not
observed. Thus, growth on non standard substrates such as miscut substrates or high index substrates have been investigated in order to achieve QDs on InP. On (113) B substrates, quantum dots in high density and with size comparable with those achieved on GaAs(001) have been obtained. Lasers with record threshold current have been obtained. However the modulation properties of the laser are not as good as predicted for ideal quantum dots lasers. Finally we present the attempts to extend the QD emission wavelength in the 2-3
μm region.
Quantum dot (QD) lasers exhibit many useful properties such as low threshold current, temperature and feedback
insensitivity, chirpless behavior, and low linewidth enhancement factor. The aim of this paper is to investigate the lasing
spectra behaviour of InAs/InP(311B) QD lasers. In order to reach the standards of long-haul transmissions, 1.55μm
InAs QD lasers grown on InP substrate have been developed. More particularly, it has been demonstrated that the use of
the specific InP(113)B substrate orientation when combined with optimized growth techniques allows the growth of very
small (4 nm high) and dense (up to 1011cm-2) QD structures. Consequently, a model based on the multi-population rate
equations (MPRE) taking into account many cavity longitudinal modes for the calculation of the entire emission
spectrum has been developed. In order to include the inhomogeneous gain broadening of the QD ensemble, various dot
populations, each characterized by a ground state (GS) and an excited state (ES) average energy level have been
considered. It will be shown that the numerical results are in good agreement with the experimental ones, both for the
case of the double laser emission and for the effects of the homogeneous broadening on the lasing spectra. This
numerical investigation based on carrier dynamics is of prime importance for the optimization of low cost sources for
optical telecommunications as well as for a further improvement of QD laser performances at 1.55-μm on InP substrate,
as already demonstrated for InAs-GaAs QD lasers emitting at 1.3-μm.
The quantum dots have added great benefits to the photonic activity, among them the decoupling between the lattice parameter of the substrate and the dot has opened the way to enlarge the spectral windows which can be accessible on different substrates. For example on a GaAs substrate a long wavelength laser emission of 1.46 μm
has been demonstrated at room temperature. The specific properties like: large material gain, large spectral
bandwidth, high speed carrier dynamics, have improved device performances. The minimum threshold current
densities of laser devices, the large spectral bandwidth of semiconductor optical amplifiers and the very high
repetition rate and very short pulse width on mode locked lasers are other benefits.
We present a new approach to achieve tunability on a 1.55 μm vertical cavity surface emitting laser (VCSEL). Tunability is achieved thanks to an electro-optic index modulator. This electro-optic material consists in a n-PDLC phase layer introduced inside the VCSEL cavity. N-PDLC comprises nematic liquid crystal dispersed in a polymer material. This first VCSEL exhibits a 10 nm tuning range and an excellent side-mode suppression ratio higher than 20
dB over the whole spectral range. The device is formed by a conventional InP-based active region with an epitaxial and a dielectric Bragg mirror. The n-PDLC layer length, close to 6 μm, is in agreement with a tunable laser emission without mode-hopping. Another decisive advantage, compared to mechanical solutions, is the tuning response time which is close to a few 10 μs to scan the full spectral range, making this device appropriate for some access network functions. Voltage values are the main limiting factor, 170 Volts have been required to obtain 10 nm tunability, but material
engineering is in progress to improve this point. We presented a first version of the device optically pumped, the next version will be electrically pumped as required for access network applications targeted here.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.