External cavity semiconductor laser with monolithic prism assembly

An optical device comprising, in combination, a single mode external cavity laser, including an anti-reflection coating on a first emitter facet of a semiconductor diode laser optically coupled to an external resonant cavity having an optical axis, an output coupler coating on a second emitter facet of the diode laser, a monolithic prism assembly in the external resonant cavity comprising a transparent optical substrate carrying a cavity-end reflective coating on one face of the substrate and a thin film Fabry-Perot interference filter on an opposing face of the substrate between the cavity-end reflective coating and the first emitter facet at an acute angle to a plane transverse of the optical axis, the thin film Fabry-Perot interference filter comprising multiple thin film reflectors sandwiching between them at least one thin film cavity layer.

A dense wavelength division multiplexing fiber-optic communication system comprising, in combination, a semiconductor diode laser optically coupled to a monolithic prism assembly in an external resonant cavity of overall length less than 10 mm, the monolithic prism assembly comprising a transparent optical substrate carrying on an internal surface a multi-cavity thin film Fabry-Perot interference angled to reflect out-of-band wavelengths away from the diode laser and comprising multiple thin film reflectors sandwiching between them at least one thin film cavity.

In an improved external cavity device including a semiconductor diode laser optically coupled to an external resonant laser cavity, having an optical axis and an optical interference filter in the cavity for locking and/or tuning the operation wavelength, .lambda., of the device, the improvement comprising a monolithic prism assembly including a transparent substrate having at least two opposing external faces, one of which incorporates the interference filter;

• and means for translating the monolithic prism assembly transversely to the optical axis, such that upon translation the operating wavelength changes, further wherein the value of M in the expression M=2L/.lambda. remains constant as .lambda. changes, where M is an integer and L is the total optical length of the cavity wherein the device operates in a single longitudinal mode.

An external cavity laser, comprising:

• an external resonant laser cavity having a length less than 10 mm;
• an optical gain medium disposed in and optically coupled to the external laser cavity;
• a monolithic prism assembly disposed in and optically coupled to the external laser cavity, including a transparent substrate, a thin film F-P interference filter incorporated on a face of the substrate and inclined at an angle to another face of the substrate, wherein the filter transmission bandwidth and the cavity length in combination are sufficient to provide single mode operation of the laser.