Real-time autocorrelator with enhanced temporal scan range for measurements of ultrashort laser pulses

A simple, low-cost light emitting diode-based quasi-real-time autocorrelator has been developed with two-fold enhancement in temporal scan range than conventional commercial autocorrelators. We use the technique of twin audio-speaker, but avoid the complex electronic circuitry to achieve two 180° out-of-phase ramp signals. Next, the use of pick-up coils, switching electronics and sum amplifier to generate a time marker signal for autocorrelation signal measurement is also dispensed with. The suitability of our setup is demonstrated by recording autocorrelation signals of ∼200 fs laser pulses from Nd:phosphate oscillator under different ramp signal voltages.