Paper MI-FrM4
Edge Emitting Spin-Lasers

Friday, October 19, 2007, 9:00 am, Room 619

Using a spin polarized current to drive a laser promises to provide threshold reduction, increased polarization of the output light, and intensity stabilization. Optically and electrically driven surface emitting lasers using InGaAs active regions have proven that indeed, spin currents can lead to threshold reduction.^1,2 We have designed and fabricated edge emitting structures based on the Fe/AlGaAs/GaAs spin injecting system to simplify and further understand this process. Samples were designed and grown to enable fabrication of either surface emitting spin-LEDs or edge emitting lasers. Specifically, a wide GaAs quantum well (QW) was grown between thick Al(35%)GaAs barriers. A 1500 Å QW serves as both a recombination region for surface emitting electroluminescence measurements and as a laser cavity for edge emitting structures. The top cladding layer is also 1500 Å, thick enough to prevent absorption by the spin injecting source, Fe, but thin enough to preserve spin injection into the recombination region. In the surface emission geometry, the behavior was similar to our standard wide-QW spin-LED structures.³ At low temperature, emission in dominated by an H-band feature,⁴ and by 20 K the emission is mainly from the bulk recombination feature. With the magnetization saturated out-of-plane, we measure electron polarizations of 24%. Cleaved cavity, gain-guided, edge emitting lasers show robust emission, however, the quality of cleaved interface greatly influences the emission spectrum.

¹Rudolph et al., Appl. Phys. Lett. 82 (2003)
²Holub et al., Phys. Rev. Lett. 98 (2007)
³van ‘t Erve et al., Appl. Phys. Lett. 89 (2006)
⁴Kioseoglou et al., Appl. Phys. Lett. 87 (2005)