Abstract: This invention relates to temperature compensated FFPs with improved means for alignment of optical fibers. The invention provides ferrule holders with shaped ferrule passageways, as components of FFP alignment fixtures, in which optical fiber ends can be readily aligned using the ferrule rotary alignment method. The ferrule holders have a composite structure facilitating temperature compensation required for applications to PZT-tuned FFPs. The ferrule holder has a core and peripheral region made of materials having different thermal expansion coefficients. The holder core in contact with the ferrule is made of a material having a thermal expansion coefficient substantially matched to that of the ferrule material. In addition, ferrule holders are provided with a means for changing the points of contact between a secured ferrule and its holder which allows wavelength drift as a function of temperature in FFPs to be adjusted.

Abstract: Compact, fixed-wavelength and tunable fiber optic lasers combine a sub-millimeter length of high-gain rare-earth-doped, sensitized glass fiber within a fiber Fabry-Perot (FFP) cavity. Tunable, single-frequency fiber lasers at 1535 nm employing high-gain erbium:ytterbium phosphate glass fiber are specifically provided. Single-frequency and/or single-polarization mode erbium:ytterbium glass fiber lasers, having cavity lengths less than about 200 .mu.m with continuous wavelength tuning range over several nanometers are provided. Amplified single-frequency lasers incorporating fiber rare-earth ion optical amplifiers are also provided. Single-frequency lasing employing sub-millimeter lengths of rare-earth doped sensitized fiber in a 3 mirror laser design is also demonstrated.

Abstract: Improved ferrule alignment fixtures for use in fiber Fabry-Perot (FFP) filters are provided. The inventive alignment fixtures have ferrule holders with shaped passageways for holding fiber-containing ferrules in three-point contact which allow fiber alignment using a rotary alignment technique.The FFPs have a fiber ferrule assembly which when aligned in the inventive ferrule holder forms an optical cavity between mirrors transverse to the fiber in the ferrule assembly. Wavelength tunable FFPs have a piezoelectric transducer interposed between the ferrule holders which can be used to change the length of the optical cavity and tune the filter.

Abstract: Temperature compensated Fiber Fabry Perot filters are provided. These filters display minimal wavelength drift over a wide range of temperatures. The temperature coefficients of the filters can be adjusted after construction. These FFPs are particularly useful in applications in which filter size is a constraint. The disclosed filter designs can be employed for minaturized filters which retain thermal and optical stability over a wide range of temperatures. In particular, low-loss thermally stable FFPs suitable for use in circuit board applications are provided.

Abstract: The present invention provides fiber Fabry-Perot filters having an adjustable temperature coefficient. Passive means and adjustable means for changing the temperature coefficients of FFPs are provided. These means allow adjustment of the temperature coefficient of the filter to minimize wavelength (or frequency) drift as a function of temperature. The means for temperature coefficient adjustment described herein are particularly useful in combination with electronic means for changing the cavity length, such as piezoelectric transducer elements. Controlling the thicknesses of epoxy used to attach PZTs in the filter fixture has been found to lead to improved reproducibility of passive temperature compensation. An adjustable means for changing the temperature coefficient of a FFP after its construction by varying the points of contact between the filter ferrules and the filter fixture is also provided.

Abstract: A single wafered optical fiber ferrule assembly useful in fixed and tunable fiber Fabry-Perot (FFP) filters is described. The ferrule assembly contains a wafered ferrule with embedded mirror and a mirrored-end ferrule which are aligned with respect to each other along a longitudinal axis in an alignment fixture. The ferrules are aligned and spaced with respect to each other to maximize transmission of light of a selected wavelength through the filter. The wafered ferrule is composed of a fiber ferrule and a wafer greater than or equal to about 5 .mu.m in thickness which are bonded together with a mirror embedded between the wafer and the ferrule. The ferrule assembly forms a FP optical resonance cavity between the two mirrors. The single wafered ferrule design produces more easily manufactured and more stable FFP than prior art designs.

Abstract: A fiber optic Fabry-Perot etalon filter constructed with a resonance cavity which is variable in length to enable variations in temperature to tune the filter to a desired frequency while maintaining accurate alignment of the fiber across the filter. Each fiber end is encased in a ferrule with the two ends placed in a facing relationship. The fibers are aligned and held by an appropriate fixture designed to allow a portion of the ferrule assembly containing the resonance cavity to expand or contract with temperature variation. The two mirrors defining the nominal size of the resonance cavity may be deposited on the facing end of each of the two ferrules, on an end of a separate waveguide located between the ends of the ferrules, or on any combination of these elements. Ferrules may be wafered, that is, a wafer of material may be bonded to the mirrored end of one or both ferrules.