Ultimate performances of an all-optical sampler based on ultrafast saturable absorbers created by heavy ion irradiation

We analyze the ultimate performances of an all-optical sampler based on ultrafast bulk GaAs saturable absorbers created by ion irradiation. The ion irradiation technique provides a unique way to adapt the sampler resolution to the optical pulse width since the absorber relaxation time can be adjusted over more than three decades with the irradiation dose. Subpicosecond time resolutions with pulse contrast of /spl sim/100 are achievable by using high irradiation doses. In standard conditions, the sampler noise performances are limited by the detector noise and sampling pulse amplitude fluctuations. Picosecond laser diode pulses with an average power of less than one microwatt are already measurable. The ultimate limit is imposed by the absorber luminescence shot noise.