Continuously grating-tuned external cavity laser with automatic suppression of source spontaneous emission and amplified spontaneous emission

A laser system comprising:

• an external cavity diode laser that comprises a dispersive unit and a gain medium, and the dispersive unit having proximal and distal sides, and the gain medium located proximally from the dispersive unit, the external cavity diode laser emitting dispersed light, and the dispersed light comprising a reflected diffraction beam and at least one of angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission;
• a guiding unit, positioned along the beam path of the reflected diffraction beam proximally from the dispersive unit;
• and
• a physical filtering device positioned along a beam path of the reflected diffraction beam that physically filters the reflected diffraction beam from the at least one of angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission to produce a low-noise laser beam.

A method comprising the steps of:

• providing an external cavity diode laser that comprises:
• a dispersive unit;
• and
• a gain element located proximally from the dispersive unit, and the external cavity diode laser emitting a reflected diffraction beam and at least one of angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission;
• guiding the reflected diffraction beam along a propagation direction using a guiding unit located proximally from the dispersive unit;
• and
• physically filtering the reflected diffraction beam from angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission.

An external cavity diode laser system comprising:

• dispersive means;
• coherent light producing means, located proximally from the dispersive unit, for producing coherent light incident upon the dispersive means, the dispersive means dispersing the incident coherent light into dispersed light, the dispersed light comprising a reflected diffraction beam and at least one of angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission;
• guiding means, located proximally from the dispersive means, for guiding the dispersed light diffracted by the dispersive means while maintaining an angular separation between the reflected diffraction beam and the at least one of angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission;
• and
• physically-filtering means for physically filtering the reflected diffraction beam from the spatially separated the at least one angularly-separated source spontaneous emission or angularly-separated amplified spontaneous emission guided to the physically-filtering means by the guiding means to produce a low-noise laser beam.