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The spin polarization modulation in birefringent vertical-cavity surface-emitting lasers (VCSELs) is investigated theoretically and experimentally for obtaining tailored polarization modulation characteristics suitable for high-speed data communications. A spin-flip rate equation analysis reveals that the spin polarization modulation response of VCSELs is flattened by shortening the electron spin relaxation time and its 3-dB bandwidth is broadened to a range determined by a frequency split between two orthogonal polarization modes. Optical modulations of spin polarized electrons in commercially-available InAlGaAs quantum well VCSELs demonstrate a wide 3-dB bandwidth of 23 GHz determined by the frequency split, which indicates that the spin relaxation time in the InAlGaAs quantum well VCSEL is around 20 ps at room temperature and suitable for use in high-speed data communications at a telecom wavelength of 1.55 μm.

Fabrication and characteristics of broader spectral width 1.3 μm and 1.5 μm InGaAsP superluminescent diodes having a novel stacked active layer (STAC-SLDs) structure are reported. The emission spectral width is successfully broadened as much as twice that of conventional SLDs, yielding spectral widths of 80 and 140 nm for the 1.3 μm and the 1.5 μm SLD, respectively.

A new, incoherent, optical negative feedback method is proposed and demonstrated for spectral linewidth reduction and optical frequency stabilization of distributed feedback lasers. The spectral linewidth and the optical frequency drift are simultaneously reduced to about 50 kHz and less than 10 MHz, respectively.