Generation of a Gaussian Schell-model field as a mixture of its coherent modes

Gaussian Schell-model (GSM) fields are examples of spatially partially coherent fields which in recent years have found several unique applications. The existing techniques for generating GSM fields are based on introducing randomness in a spatially completely coherent field and are limited in terms of control and precision with which these fields can be generated. In contrast, we demonstrate an experimental technique that is based on the coherent mode representation of GSM fields. By generating individual coherent eigenmodes using a spatial light modulator and incoherently mixing them in a proportion fixed by their normalized eigenspectrum, we experimentally produce several different GSM fields. Since our technique involves only the incoherent mixing of coherent eigenmodes and does not involve introducing any additional randomness, it provides better control and precision with which GSM fields with a given set of parameters can be generated.