Abstract: A frequency-stabilized laser source that is adapted for use as a frequency standard. The frequency of the laser source is locked and the laser beam delivered by the laser source on a transition of an absorber chemical element. The technique combines both operation with saturated absorption and synchronous detection, based on modulating said transition being saturated by the beam passing through the absorber chemical element. This produces a single frequency laser beam whose output frequency is stationary. The frequency is not continuously modulated and is more precise than that which would be obtained operating with single-pass absorption only. The laser source is thus adapted for making a frequency standard.

Abstract: The light-emitting device has a fiber stub part, a semiconductor optical amplifying device, a photodiode, and a bench as its main parts. The fiber stub part is composed of a ferrule and a grating fiber. The fiber stub part and the semiconductor optical amplifying device are mounted on the bench, and optically coupled together. An optical cavity is composed of the light-reflecting face of the semiconductor optical amplifying device and the diffraction grating of the grating fiber. The light-emitting device, which does not use a pigtail fiber, can be downsized and can provide laser light with a desired wavelength.