The characteristic optical transmission properties of crystal fibres grown by the laser-heated miniature growth technique are summarized. They convert an incident Gaussian beam to one possessing complex spatial intensity and polarization modulation by total internal reflection, birefringence and diffraction. Phase conjugation is demonstrated as a method of restoring the transmitted beam's intensity profile and polarization to that originally incident, enabling such fibres to be used as miniature laser media in phase conjugate cavities.