Search

We have demonstrated fixed-current operation of a vertical-cavity surface-emitting laser (VCSEL) transmitter operating at 1.25 Gb/s over a wide temperature range by using an elevated-oxide-layer structure. Four different types of oxide VCSELs have been prepared for the transmitter modules; conventional-oxide and elevated-oxide-layer VCSELs with the oxide-aperture diameter of 6.6 and 10 μm, and their temperature dependence of the threshold current and turn-off transient responses have been measured. Approximately 10%-reduced both fall time and timing jitter mainly originating from the alleviated turn-off-induced abnormalities in the elevated-oxide-layer VCSEL transmitters contributed to achieve the fixed-current operation in the temperature range from 20 °C to 80 °C. Although the operating current of the elevated-oxide-layer VCSEL transmitter should be increased as the threshold current increases, a simple driving circuit owing to the fixed-current operating transmitter over a wide temperature range will bring a drastic energy saving in the optical data transmission system that incorporates VCSEL as a light source. [ABSTRACT FROM PUBLISHER]

Degradation in wavelength accuracy and single-mode stability, incurred by random fluctuation of grating period, has been studied by an effective-index transfer matrix method in quarter wavelength shifted distributed-feedback lasers. The laser facets are assumed to be perfectly antireflection coated, and the period fluctuation is modeled as a Gaussian random variable. Laser wavelength variation originates from period-fluctuation induced wavelength change and threshold gain variation. Threshold gain difference decreases with increasing period fluctuation irrespective of grating coupling coefficient, while spatial-hole-burning effect is exacerbated or alleviated in low- and high-coupling coefficient devices, respectively [ABSTRACT FROM PUBLISHER]