Measurement of the core proximity in polished fiber substrates and couplers.

We report recent developments in a technique to measure the thickness of cladding remaining on polished singlemode fiber substrates. This technique relies on the measurement of the throughput attenuation resulting when a drop of liquid of appropriate refractive index is placed on the substrate. Applications to fiber couplers and other all-fiber devices are described.

All-single-mode fiber resonator.

An all-fiber-ring resonator has been constructed using a single strand of single-mode optical fiber and a directional coupler. Derivation of the resonator finesse in terms of fiber and directional coupler parameters is given. A finesse of 80 has been achieved experimentally. Applications of such a fiber-ring resonator are discussed.

All-fiber stimulated Brillouin ring laser with submilliwatt pump threshold.

An all-fiber ring resonator, constructed from a single strand of single-mode optical fiber and a directional coupler, is shown to have a low threshold for stimulated Brillouin laser action. The 10-m-perimeter fiber ring resonator has a low round-trip loss of under 3.5% and an inherent pump-power enhancement of approximately 30. Lasing threshold for the 4.0-microm-core fiber occurred with a pump power of 0.56 mW at lambda = 6328 A and 1.74 mW at lambda = 5145 A.