Optical Polarization Modulation and Gain Anisotropy in an Electrically Injected Spin Laser

Abstract

The effects of spin-induced gain anisotropy on output polarization and threshold current reduction of electrically pumped spin-polarized lasers have been studied. Analytical forms of these parameters are derived by considering diffusive transport from the spin injector to the active region. The calculated values of the parameter are in excellent agreement with values obtained from measurements made at 200 K on an InAs/GaAs quantum dot spin-polarized vertical cavity surface-emitting laser. Electrical modulation of the output polarization of the laser is demonstrated with a peak modulation index of 0.6.

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

“…[23][24][25][26] Threshold reduction is also one of the first predicted and observed characteristics of spin-VCSELs. 23,[27][28][29] Furthermore, these lasers provide ultrafast dynamics 30 and enhanced emission intensities. 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.…”

“…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.…”

Novel closed-form solution for spin-polarization in quantum dot VCSEL

“…At high temperatures, the electron spin relaxation time is determined by the D'yakonovPerel' (DP) spin scattering process [17]. The main mechanisms that govern the carrier spin-flip relaxation include exchange interaction, motional narrowing due to the lack of inversion symmetry, and mixing between the conduction and valence band states through spin-orbit coupling [27].…”

“…A spin-VCSEL, with InAs/GaAs selforganized quantum dots as the active gain media and MnAs/GaAs Schottky tunnel contact, has been fabricated and characterized in [16] for a laser operating at 200 K. The measured degree of circular polarization in the output is 8% and the maximum threshold current reduction is 14%. The effects of spin-induced gain anisotropy on the output polarization and threshold current reduction of electrically pumped spin-polarized lasers are reported in [17]. Electrical modulation of the output polarization of the laser has also been demonstrated in [17] with a peak modulation index of 0.6.…”

“…The effects of spin-induced gain anisotropy on the output polarization and threshold current reduction of electrically pumped spin-polarized lasers are reported in [17]. Electrical modulation of the output polarization of the laser has also been demonstrated in [17] with a peak modulation index of 0.6. Saha et al [18] have studied the high-frequency dynamics of spin-polarized carriers and photons in InAs/GaAs spin laser.…”