Ultrafast carrier capture at room temperature in InAs∕InP quantum dots emitting in the 1.55μm wavelength region

Abstract

The energy and excitation density dependence of the carrier dynamics in self-assembled InAs∕InP quantum dots (QDs), emitting in the 1.55μm wavelength region, is investigated by means of time-resolved pump-probe differential reflection spectroscopy at room temperature. We observe ultrafast carrier capture and subsequential carrier relaxation into the QD ground state within 2.5 ps. The carrier lifetime in the QDs strongly depends on the QD optical transition energy within the QD ensemble as well as the carrier density, and ranges from 560 up to 2600 ps.

Low density 1.55 μm InAs/InGaAsP/InP (100) quantum dots enabled by an ultrathin GaAs interlayer

“…The deduced lifetimes are 2.2 and 10.6 ns. 2.2 ns is related to the lifetime of the QDs, which is in the range of values observed for similar QDs, 12,13 revealing high optical quality. The lifetime of 10.6 ns could be related to the coupling between the bright and dark exciton states.…”

Measurement and analysis of optical gain spectra in 1.6 to 1.8 μm InAs/InP (100) quantum-dot amplifiers

“…All the values of the parameters used in the simulations are given in Table 1. The number used for the FWHM of the inhomogeneous broadening 0 is based on time resolved differential reflection spectroscopy measurements and photoluminescence (PL) measurements at 4.8K applied on similar QD (Bogaart et al 2005). The FWHM of the homogeneous broadening 2h cv is not known from previous research.…”

“…Carrier recombination time in ES and GS τ r = 1 ns (Bogaart et al 2005) Quantum dot density N D = 3. are the transition matrix elements of the GS and ES recombination (Sugawara et al 2000); B cv the Lorentzian homogenous broadening function (Sugawara et al 2000) with a 2h cv FWHM and E m the recombination energy of the m-th spectral group. The total modal gain for each spectral group G m could be calculated with:…”

“…C g = πe 2h /cn r ε 0 m 2 0 is a constant; N W is the number of QD layers; H act is the average active quantum dot layer thickness; |P σ G S,E S | 2 Capture time from WL to ES τ c0 = 1 ps (Bogaart et al 2005) Capture time from ES to GS τ d0 = 1 ps (Bogaart et al 2005) Carrier escape time from WL to SCH τ qe =3 ns (Gioannini and Montrosset 2007) Carrier recombination time in SCH τ sr = 4.5 ns (Gioannini and Montrosset 2007) Carrier recombination time in WL 2 ps < τ qr < 100 ps Fit…”

“…These advantages are due to the three dimensional carrier confinement in QDs. Some of the benefits that have been experimentally demonstrated are a comparatively low lasing threshold current density (Liu et al 1999) and ultra fast gain recovery in optical amplifiers (Borri et al 2000;Bogaart et al 2005). Another major advantage of QDs over bulk or quantum well material is the wavelength tunability.…”