Ultrafast gain dynamics in InP quantum-dot optical amplifiers

Langbein, Wolfgang Werner; Cesari, Valentina; Masia, Francesco; Krysa, A. B.; Borri, Paola; Smowton, Peter M.

doi:10.1063/1.3518715

Cited by 15 publications

(8 citation statements)

References 11 publications

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“…S5. The former is required for single mode waveguide samples, such as semiconductor optical amplifiers, and has been used by us for a variety of different samples 16,17,[48][49][50][51][52] . It is also used for FWM imaging of nanoparticles which we reported in Ref.…”

Section: Optical Setupmentioning

confidence: 99%

Giant exciton oscillator strength and radiatively limited dephasing in two-dimensional platelets

et al. 2015

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We measured the intrinsic ground-state exciton dephasing and population dynamics in colloidal quasi-two-dimensional (2D) CdSe nanoplatelets at low temperature (5-50 K) using transient resonant four-wave mixing in heterodyne detection. Our results indicate that below 20 K the exciton dephasing is lifetime limited, with the exciton population lifetime being as fast as 1 ps. This is consistent with an exciton lifetime given by a fast radiative decay due to the large in-plane coherence area of the exciton center-of-mass motion in these quasi-2D systems compared to spherical nanocrystals. The radiative rate in such 2D platelet systems can be controlled by the platelet area over orders of magnitude

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Section: Optical Setupmentioning

confidence: 99%

Giant exciton oscillator strength and radiatively limited dephasing in two-dimensional platelets

et al. 2015

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“…In this context and the context of the single-photon amplifier, it is important to understand the intrinsic relaxation mechanisms which can influence preparation and readout of the few-particle quantum states via ultrashort light pulses. To this end, charge-carrier dynamics in QDs based on III-V semiconductors with shallow quantum confinement has been studied both in large ensembles [18][19][20] and single specimens [7,[21][22][23][24][25][26]. These developments have culminated in demonstrations of optical writing and readout of spin states in single or coupled QDs [13][14][15][16][17]27].…”

Section: Introductionmentioning

confidence: 99%

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

et al. 2018

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We study the dynamics of photoexcited electrons and holes in single negatively charged CdSe/ZnSe quantum dots with two-color femtosecond pump-probe spectroscopy. An initial characterization of the energy level structure is performed at low temperatures and magnetic fields of up to 5 T. Emission and absorption resonances are assigned to specific transitions between few-fermion states by a theoretical model based on a configuration interaction approach. To analyze the dynamics of individual charge carriers, we initialize the quantum system into excited trion states with defined energy and spin. Subsequently, the time-dependent occupation of the trion ground state is monitored by spectrally resolved differential transmission measurements. We observe subpicosecond dynamics for a hole excited to the D shell. The energy dependence of this D-to-S shell intraband transition is investigated in quantum dots of varying size. Excitation of an electron-hole pair in the respective p shells leads to the formation of singlet and triplet spin configurations. Relaxation of the p-shell singlet is observed to occur on a time scale of a few picoseconds. Pumping of p-shell triplet transitions opens up two pathways with distinctly different scattering times. These processes are shown to be governed by the mixing of singlet and triplet states due to exchange interactions enabling simultaneous electron and hole spin flips. To isolate the relaxation channels, we align the spin of the residual electron by a magnetic field and employ laser pulses of defined helicity. This step provides ultrafast preparation of a fully inverted trion ground state of the quantum dot with near unity probability, enabling deterministic addition of a single photon to the probe pulse. Therefore our experiments represent a significant step towards using single quantum emitters with well-controled inversion to manipulate the photon statistics of ultrafast light pulses.

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“…InP/GaInP QD materials have also shown ultrafast absorption recovery times, which has allowed their use as semiconductor saturable absorber mirrors, for example, to mode-lock Ti: Sapphire lasers [9]. In addition, the gain recovery time for InP QDs has been shown to be even faster than for InAs QDs, dominated by a sub-200 fs component [10]. The potential for ultrafast electrically-pumped monolithic mode-locked QD lasers operating at visible wavelengths where there are numerous applications requiring short optical pulses have yet to be Z. Li, C. P. Allford, S. Shutts, R. Alharbi and P. S. Smowton are with School of Physics & Astronomy, Cardiff University, Cardiff, CF24 3AA, UK (liz74@cardiff.ac.uk; allfordcp1@cardiff.ac.uk; shuttss@cardiff.ac.uk; alharbirs@cardiff.ac.uk; smowtonpm@cardiff.ac.uk).…”

Section: Introductionmentioning

confidence: 99%

Monolithic InP Quantum Dot Mode-Locked Lasers Emitting at 730 nm

Allford

Shutts

et al. 2020

IEEE Photon. Technol. Lett.

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This letter reports on InP/GaInP quantum dot modelocked lasers emitting in the 730 nm wavelength region, extending the spectral range of previously reported monolithic mode-locked edge-emitting lasers. Modal gain and absorption measurements were used to identify a relatively broad spectrum which is utilised to support passive mode-locking in a monolithically integrated two-section ridge laser. The conditions for mode-locking were explored by varying the current to the gain section and reverse bias to the absorber section. For a total cavity length of 3 mm, the shortest pulse train observed was 6 ps in duration with a repetition rate of 12.55 GHz.

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Ultrafast gain dynamics in InP quantum-dot optical amplifiers

Cited by 15 publications

References 11 publications

Giant exciton oscillator strength and radiatively limited dephasing in two-dimensional platelets

Giant exciton oscillator strength and radiatively limited dephasing in two-dimensional platelets

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

Monolithic InP Quantum Dot Mode-Locked Lasers Emitting at 730 nm

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