Circularly polarized lasing in a (110)-oriented quantum well vertical-cavity surface-emitting laser under optical spin injection

Abstract

We fabricated and characterized a vertical-cavity surface-emitting laser (VCSEL) based on (110) InGaAs/GaAs multiple quantum wells (MQWs). Circularly polarized lasing in the (110) VCSEL by optical injection of spin-polarized electrons has been demonstrated at 77 K and room temperature. A high degree of circular polarization, 0.94, was observed at 77 K, reflecting the long electron spin relaxation time in the (110) MQWs.

Room temperature circularly polarized lasing in an optically spin injected vertical-cavity surface-emitting laser with (110) GaAs quantum wells

“…8,12 The s of 0.7 ns at the lasing threshold is, however, still longer than the lasing duration of 0.2 ns. At the same pump intensity, the carrier lifetime c was 1.8 ns, which was fiftyfold longer than that in the ͑110͒ InGaAs QWs ͑40 ps͒, 6 and this reflects the high-quality MBE growth of the ͑110͒ GaAs QWs. The measured initial P s decreased from 0.3 to 0.04 when the I ex increased from 0.2 to 4.0 kW/ cm 2 .…”

“…We previously reported a high degree of circular polarization of 0.94 at 77 K when using ͑110͒ InGaAs/GaAs QWs with a long s of 2.8 ns as the gain medium. 6 However, only a low degree of circular polarization of 0.42 was obtained at RT, which was attributed to a short s of 0.4 ns. The carrier lifetime ͑ c ͒ was 40 ps at RT, indicating the low quality of the ͑110͒ InGaAs QWs.…”

1300 nm optically pumped quantum dot spin vertical external-cavity surface-emitting laser

“…31,32 The attributes of spinVCSELs offer the potential for new applications such as reconfigurable optical interconnects, spin-dependent switches for optical telecommunications, quantum information processing and data storage, quantum computing, bandwidth enhancement, high speed modulators, cryptography of optical communication, circular dichroism spectroscopy, biological structure studies, biomedical sensing, and advanced optical devices. 8,15 Spin-polarized VCSELs have previously been demonstrated at short wavelengths either electrically driven via spin-polarized current into quantum dot (QD) 29,32,33 and quantum well (QW) 34,35 active regions or optically by optically pumping a QW 18,20,27,28,36,37 or bulk 17 VCSEL. In contrast, at telecoms wavelengths, we are only aware of one recent report of a 1300 nm optically pumped QW spin-VCSEL at room temperature.…”

Mapping between quantum dot and quantum well lasers: From conventional to spin lasers

“…Here, for simplicity, we also focus mostly on the infinitely long spin relation times for electrons (in the QW, WL, and QD regions). This limiting case can accurately describe recent experiments, 67,68 in which the spin relaxation time for electrons is not only much longer than for holes, but also much longer than the other characteristic timescales for the carriers.…”