  Gaussian Schell-model fields are examples of spatially partially coherent
fields, which in recent years have found several unique applications. The
existing techniques for generating Gaussian Schell-model (GSM) fields are based
on introducing randomness in a spatially completely coherent field and are
limited in terms of control and precision with which GSM 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 modes and mixing them in proportion fixed by their coherent mode
representation, we experimentally demonstrate generation of several GSM fields.
Since our technique involves only mixing of coherent eigenmodes and does not
involve introducing randomness from outside, it provides much better control
and precision with which GSM fields with a given set of parameter could be
generated.
