Abstract

A novel form of electromagnetic field analyser is proposed and demonstrated. The analyser is based on the use of a coherent local oscillator which is tuneable, in an orthogonal spatial mode sense. The propagation of a complex transverse electromagnetic field F(x,y) can be described in terms of a set of orthogonal spatial modes: Here, E_p(x,y) is the p^th mode of the set; A_p is its modulus and ϕ_p its phase. Figure 1, illustrates the situation where this field is coherently mixed with the mode E_q(x.y) from a mode tuneable local oscillator.

© 1996 IEEE