Digitally Adjustable Laser Diode Driver Circuit with 9 ps Resolution

Laser pulses are essential in various scientific fields, yet existing laser diode drivers offer limited adjustability. This paper presents a digitally adjustable subnanosecond gain-switched laser diode driver, a first one with step sizes of the control being in the single-digit picosecond range. The proposed circuit differentially drives the laser diode (LD) using two high-current gate drivers whose relative delay is digitally adjusted by a dual programmable delay line. Pulse width is defined by the delay difference between the two channels, enabling fine control without the need for high-speed semiconductor switching. Experimental results demonstrate stable optical pulse generation with widths tunable from 350ps to 2.8ns in 9ps increments and repetition rates exceeding 150MHz. Timing jitter remains below 15ps, and amplitude variation is below 1% across the tested operating conditions. The proposed solution provides a compact, low-cost, and highly adjustable platform for applications that require precise timing and pulse-width control, such as time-resolved measurements, range finding, and nonlinear optical excitation.