Ion-implanted GaAs for ultrafast saturable absorber applications

The status of our work on arsenic and oxygen implanted GaAs for ultrafast saturable absorber applications is reviewed. We show that the response time and absorption modulation are both reduced by implantation whilst the nonbleachable losses increase. Similar combinations of response time and modulation can be achieved using either ion species and various combinations of dose and annealing temperatures. Furthermore, it is shown that, in order to exploit the full capacity of this material, amorphisation during implantation should be avoided, and the samples should be annealed afterwards, leading to the predominance of point defects. We give several guidelines to the creation of a high performance GaAs saturable absorber through ion-implantation. Response times <400 fs are achievable while still maintaining 80% of the absorption modulation of unimplanted GaAs.