System and techniques for diode laser wavelength spectrum narrowing

Abstract

A diode laser system employing a vapor cell in an external cavity and related techniques are disclosed. The system may be configured to provide high-power, multi-mode output within one or more narrow ranges of wavelengths. A beam emitted from the laser along an initial optical axis passes through a vapor cell, where the effective ground-state occupation density of the vapor is reduced, causing spatial gradients of the vapor's effective index of refraction. Refraction of rays passing through these gradients produces angular deflections, most significantly for rays where the gradients are strongest and for wavelengths whose index of refraction departs furthest from unity near these atomic transitions. An at least partially reflective surface which is not aligned with the initial optical axis but rather is aligned perpendicular to some of these deflected rays provides feedback within an angular range, thereby contributing to the gain of the laser source for these wavelengths.