Full mapping of optical noise in photonic devices: an evaluation by near-field scanning microscopy

We demonstrate the possibility of mapping the transverse spatial distribution of optical noise at the output of photonic devices. Maps of local low-frequency noise are obtained by using statistics on multiple-sampling data from near-field scanning optical microscopy (NSOM). On selected laser diodes, the signatures of basic types of transverse mode instabilities (relative phase and amplitude of modes) are unambiguously obtained. On more complex systems, the types of mode instability can be identified and their intensity can be monitored. Such noise mapping opens a new path for analyzing noise origins and for optimizing device design.