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(a) VCSEL transient response for a fixed pump power of 41 mW after excitation of spin-polarized (solid line) and unpolarized (dotted line) electrons, respectively. The VCSEL emission intensity is largely increased for spin-polarized electrons. (b) Experimental VCSEL characteristic curve for the determination of laser threshold. The room-temperature VCSEL exhibits a clear threshold reduction for pumping with 50% spin-aligned electrons (solid line) in comparison to unpolarized electrons (dotted line).
(a) Calculated characteristic curve for the same conditions as in the experiment. The phenomenological model describes the experiment well and reproduces the experimental threshold reduction. (b) Calculated characteristic curves for pulsed excitation and spin relaxation times up to 800 ps. The threshold reduction is clearly limited by spin relaxation in the laser structure. A threshold reduction of 50% is possible for spin relaxation times and a 100% spin-polarized source.
(a) Room-temperature spin relaxation time of undoped (110) GaAs QWs vs electron confinement energy at low excitation density. (b) Room-temperature spin relaxation time vs excitation density for 7.0 nm and 8.5 nm wide (110) GaAs QWs. At high densities, the PL polarization degree is very small due to bleaching. Please note that this implicates that the obtained values of are not exact (see Ref. 25).
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