Use of commercial grade light emitting diode in auto-correlation measurements of femtosecond and picosecond laser pulses at 1054 nm

Commercial grade AlGaAs based light emitting diodes (LEDs) have been characterized at 1054 nm for their non-linear photoconductivity and effect of aging and used as a two-photon detector to record auto-correlation signals of ultra-short laser pulses. The lifetime of these LEDs is found to be ∼6 × 1011 and ∼2 × 1011 laser pulses at an average incident power level of 20 and 60 mW of 200 fs laser pulses, respectively. These LEDs have been used for real time recording of interferometric auto-correlation (IAC) to determine pulse duration and sensitive detection of the frequency chirp of 200 fs laser pulses. A twofold enhancement in sensitivity of new modified signal, derived from the envelope functions of IAC signal, has been achieved. The suitability of these LEDs to record intensity auto-correlation in multi-picosecond regime is also demonstrated using 30ps laser pulses from an Nd:YLF oscillator.