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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.

1.25 Gb/s optoelectronic full-triplex transceiver module with planar-lightwave-circuits was designed and fabricated for the fiber-to-the-home services according to G/E-PONs standards. A low electrical crosstalk of the critical characteristics for the reliable operation of the 1.25 Gb/s full-triplex transceiver module is intensively investigated because the electrical crosstalk on a resistive silicon substrate is more serious than that on a dielectric substrate. It is observed that the performances of the transmitter and receiver satisfy the transmitter and receiver specifications defined in the standards. From this proposed module layout, a design convenience as well as a great reduction of the silicon substrate size by about 50% was completely achieved. Consequently, the 1.25 Gb/s full-triplex transceiver module was fabricated with electrical and mechanical packaging technologies such of a low crosstalk design and a passive alignment method.