We describe a practical implementation of a (semi-deterministic) photon gun
based on stimulated Raman adiabatic passage pumping and the strong enhancement
of the photonic density of states in a photonic band-gap material. We show that
this device allows {\em deterministic} and {\em unidirectional} production of
single photons with a high repetition rate of the order of 100kHz. We also
discuss specific 3D photonic microstructure architectures in which our model
can be realized and the feasibility of implementing such a device using
Er3+ ions that produce single photons at the telecommunication
wavelength of 1.55μm.Comment: 4 pages, 4 EPS figure