Abstract: A digital driver circuit with increased maximum output voltage amplitude and therefore also increased maximum current amplitude for constant power supply voltages is provided. A current sensing resistor replaces the conventional current source transistor in the output stage of the driver circuit. In addition, the output current control circuit is applied to an earlier stage of the driver. An automatic output current control scheme is created which keeps the voltage across the current sensing resistor equal to a DC reference and therefore maintains the output current or voltage amplitude by actively level shifting the DATA and DATA drive signals for the output stage to the correct level. This eliminates the necessity to incorporate a voltage safety margin and simultaneously increases the maximum available output voltage amplitude.

Abstract: An amplitude control scheme for a high bit rate digital optical transmitter is disclosed. The data to be transmitted by the laser is pulse-width modulated by a low frequency signal. The pulse-width modulated signal is applied to the laser via a laser driver and to a mark density reference generator. The magnitude of the low frequency components from the mark density reference generator is a signal indicative of the desired amplitude of the laser light pulses. A back-face photodiode converts a portion of the laser light into an electrical signal, the magnitude of the low frequency portion thereof being a signal indicative of the actual amplitude of the laser light pulses. The actual amplitude of the laser light pulses is compared to the desired amplitude and the laser driver output amplitude may then adjusted to compensate for variations in the laser performance.

Abstract: An amplitude control scheme for a high bit rate digital optical transmitter is disclosed. The data to be transmitted by the laser is pulse-width modulated by a low frequency signal. The pulse-width modulated signal is applied to the laser via a laser driver and to a mark density reference generator. The magnitude of the low frequency components from the mark density reference generator is a signal indicative of the desired amplitude of the laser light pulses. A back-face photodiode converts a portion of the laser light into an electrical signal, the magnitude of the low frequency portion thereof being a signal indicative of the actual amplitude of the laser light pulses. The actual amplitude of the laser light pulses is computed to the desired amplitude and the laser driver output amplitude may then adjusted to compensate for variations in the laser performance.

Abstract: A technique for increasing the number of manufactured laser transmitters which meet a predetermined wavelength specification is disclosed. Semiconductor lasers which exhibit a relationship between operating temperature and wavelength can be tuned by adjusting the operating temperature to ensure that the transmitter's operating wavelength will fall within the system-specified limits.

Abstract: Disclosed is means for driving a laser whereby a dc bias current is supplied to keep the laser normally above threshold, and a modulation current brings the laser below threshold when a pulse appears. In one embodiment, a feedback controlled bias current source (11) and modulation current source (15) are coupled to the p-side terminal of the laser (10) while a constant voltage source (27) is coupled to the n-side terminal of the laser in a way which results in subtraction of the modulation current from the dc bias current. This mode of operation essentially eliminates laser overshoot and more nearly equalizes rise and fall times of the light pulses.

Abstract: The timing pattern of incoming pulses is modified by amplifying the pulses, selectively shifting the dc potential of the amplified pulses, and clipping or slicing the amplified pulses at a predetermined potential. The thus clipped or sliced output pulses have a predetermined timing pattern at a predetermined dc level,resulting in a time pattern correction of the incoming pulses.