We demonstrate mode-division multiplexed WDM transmission over 50-km of few-mode fiber using the fiber’s LP₀₁ and two degenerate LP₁₁ modes. A few-mode EDFA is used to boost the power of the output signal before a few-mode coherent receiver. A 6×6 time-domain MIMO equalizer is used to recover the transmitted data. We also experimentally characterize the 50-km few-mode fiber and the few-mode EDFA.

A Bragg grating in a single-mode polymer optical fiber (POF) has been created. The novel grating has a length of 1 cm with a reflectivity of 80% and a linewidth of about 0.5 nm. The wavelength tunability of the POF grating by stretching was investigated and a wavelength tunable range of 20 nm has been achieved. Based on the properties of the polymer, we believe that this kind of grating has a wavelength tuning potential of more than 100 nm.

A novel and highly sensitive liquid level sensor based on a polymer optical fiber Bragg grating (POFBG) is experimentally demonstrated. Two different configurations are studied and both configurations show the potential to interrogate liquid level by measuring the strain induced in a POFBG embedded in a silicone rubber diaphragm, which deforms due to hydrostatic pressure variations. The sensor exhibits a highly linear response over the sensing range and a good repeatability. For comparison, a similar sensor using a FBG inscribed in silica fiber is fabricated, which displays a sensitivity that is a factor of 5 smaller than the POFBG. The temperature sensitivity is studied and a novel multi-sensor arrangement proposed which has the potential to provide level readings independent of temperature and the liquid density.

We demonstrate a distributed sensing network with 500 identical ultra-weak fiber Bragg gratings (uwFBGs) in an equal separation of 2m using balanced Michelson interferometer of the phase sensitive optical time domain reflectometry (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3 × 3 coupler demodulation. Lab experiments on detecting sound waves in water tank are carried out. The results show that this system can well demodulate distributed acoustic signal with the pressure detection limit of 0.122Pa and achieve an acoustic phase sensitivity of around −158dB (re rad/μPa) with a relatively flat frequency response between 450Hz to 600Hz.

Static soliton states in twin-core nonlinear optical fibers are examined using an improved variational approximation: the soliton’s width is an additional varying parameter, together with the ratio of the energies in, and the phase difference between, the two cores. For the symmetric coupler, results agree well with numerical ones; in particular, the bifurcation between symmetric and asymmetric solitons is shown to be slightly subcritical. For the asymmetric coupler, the control parameters are the difference between the cores’ dispersion coefficients and the phase velocity mismatch. Soliton states in the asymmetric coupler show a strong and easily controlled bistability. The soliton exists for some energies even when one of the cores has normal dispersion. © 1996 The American Physical Society.

In this work we experimentally investigate the response time of humidity sensors based on polymer optical fiber Bragg gratings. By the use of etching with acetone we can control the poly (methyl methacrylate) based fiber in order to reduce the diffusion time of water into the polymer and hence speed up the relative wavelength change caused by humidity variations. A much improved response time of 12 minutes for humidity decrease and 7 minutes for humidity increase, has been achieved by using a polymer optical fiber Bragg grating with a reduced diameter of 135 microns.