A single-frequency, diode-pumped, Er-Yb:glass microchip laser at a 1530-nm wavelength has been designed and operated. An output power of greater than 25 mW, a linewidth narrower than 1 kHz, and a slope efficiency of 22% have been obtained.

Benefits provided by higher order bidirectional Raman pumping schemes in 10-Gb/s unrepeated wavelengthdivision-multiplexing transmission systems are experimentally quantified in terms of BER performances at 10 Gb/s. By keeping under control double-Rayleigh-scattering-noise-induced transmission penalties, which can degrade system performance at very high ON-OFF Raman gain, as well as nonlinear propagation effects such as Brillouin scattering, self-and cross-phase modulations, four-wave-mixing, and Raman-induced crosstalks, we show a total unrepeated system reach enhancement up to 3.5 dB with respect to first-order bidirectional pumping. As confirmed by theory, the maximum reach enhancement is mainly limited by pump-to-signal relative intensity noise transfer induced by higher order copumping.

Abstract:We propose a new Raman based distributed measurement technique which allows for temperature sensing over nearly 40 km of graded index multimode optical fiber with meter-scale spatial resolution and temperature accuracy better than 3°C.

The performance of distributed temperature sensor systems based on spontaneous Raman scattering and coded OTDR are investigated. The evaluated DTS system, which is based on correlation coding, uses graded-index multimode fibers, operates over short-to-medium distances (up to 8 km) with high spatial and temperature resolutions (better than 1 m and 0.3 K at 4 km distance with 10 min measuring time) and high repeatability even throughout a wide temperature range.

Single-mode operation of a continuous-wave Er:Yb:phosphate glass laser pumped at 980 nm by a InGaAs index-guided diode laser has been achieved for what is to our knowledge the first time. The maximum output power obtained at 1540 nm is 10 mW, and the width of the spectral line is less than 15 kHz.