Fields in extended cavity lasers

The electromagnetic fields for an extended-cavity laser are described precisely and in detail. The extended-cavity laser consists of a semiconductor laser diode with a partially reflecting coating on one facet and an antireflection coating on the other coupled by radiation through a lensed-fiber, single-mode guide to another partially reflecting coating terminating a narrow-wavelength filter. The formulation is based on the Lorentz reciprocity theorem, the fields are described by angular plane-wave spectra, and the equivalent transmission line representation is used to determine the fields reflected and transmitted by partially reflecting and antireflection coatings. The design of antireflection coatings is considered in detail, and a formula which gives the optimum distance from the diode antireflection coating to an inline lensed fiber is derived