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HL: Fachverband Halbleiterphysik

HL 39: Optical properties

HL 39.3: Vortrag

Dienstag, 12. März 2013, 10:45–11:00, H13

Intensity fluctuations of a semiconductor laser at threshold - accessing critical dynamics with higher order noise spectroscopy — Sebastian Starosielec, Jörg Rudolph, and •Daniel Hägele — AG Spektroskopie der kondensierten Materie, Ruhr-Universität Bochum, Bochum, Germany

We investigate the intensity fluctuations I(t) of an electrically driven single mode vertical cavity emitting laser that serves as a model system for critical dynamics at a second order phase transition [1]. Simulations of the fourth order frequency resolved correlation spectrum S^(corr)(ω,ω′) = ⟨ I_ωI_ωI_ω′ I_ω′⟩ − ⟨ I_ωI_ω⟩ ⟨ I_ω′ I_ω′ ⟩ reveal a characteristic structure in the spectrum at threshold and almost no structure below and above threshold. Measurements of S^(corr)(ω,ω′) with a bandwidth of 90 MHz and real time data processing (see [2]) are in good agreement with theory for all investigated lasers. Making use of modern electronics and data processing, we resolve for the first time pump-dependent features in a fourth order spectrum that were inaccessible before. Our experimental approach may open new routes for investigating temporal fluctuations at phase transitions in many systems including magnets and superconductors.
[1] V. DeGirogio and M. O. Scully, Phys. Rev. A 2, 1170 (1970)
[2] S. Starosielec et al., Rev. Sci. Instrum. 81, 125101 (2010)