Aydin Yeniay

Spontaneous and stimulated Brillouin scattering gain spectra in optical fibers

We study the Brillouin scattering behavior in several single-mode fibers with different waveguide characteristics in terms of their longitudinal mode structures in the gain spectrum, linewidth narrowing, and stimulated Brillouin scattering (SBS) threshold levels. Evolution from spontaneous to SBS is investigated by monitoring the Brillouin line-shape and the behavior of the longitudinal acoustooptic resonance modes that exist in the core. We compare our results with the current theory of Brillouin scattering generated from noise in the undepleted pump approximation. We also present experimentally Brillouin gain spectra in the highly depleted pump regime, where there is no analytical solution, by showing the evolution of the gain spectrum as a function of the injected laser intensity.

Ultra low loss polymer waveguides

Single-mode perfluoropolymer waveguide structures exhibiting a polarization-independent ultra low loss of <0.05 dB/cm at 1310 nm and <0.07 dB/cm at 1550 nm with a /spl Delta/n of 1.6% have been fabricated for the first time. These new low-loss structures indicate relatively high-power-handling reliability at 1310 and 1550 nm. Based on this, a highly efficient arrayed-waveguide grating multi-demultiplexer with a crosstalk of 30/spl plusmn/2 dB and an insertion loss of 2.8/spl plusmn/0.3 dB is realized.Perfluoropolymer waveguide structures exhibiting polarization independent ultra low loss of <0.05 dB/cm at 1310 nm and <0.07 dB/cm at 1550 nm have been fabricated for the first time. These new low loss structures indicate relatively high power handling reliability.

Duty cycle ratio dependence on the performance of a Q-switched laser with an Er 3+ –Yb 3+ codoped glass waveguide

We examine the performance of a hybrid Q-switched LiNbO(3) and Er(3+)-Yb(3+) doped glass waveguide laser as a modulation function of the duty cycle ratio. As the duty cycle ratio decreases, the laser operates at higher peak power and pulse width. At low duty cycle ratio (<1%), we observe variations in the Q-switched pulse shape; while the laser produces 59-W and 200-ns pulses to a 1-kHz repetition rate for a 50% duty cycle, it yields 27-W and 100-ns pulses to a 10-kHz repetition rate for a 0.01% duty cycle.

Nanoporosity effect in optical loss of single-mode polymer waveguides.

We fabricate single-mode polymer waveguide structures exhibiting polarization-independent ultra-low loss of 0.04 and 0.05 dB/cm at the 1310 and 1550 nm bands, respectively, with a Deltan of 1.6%. A porous structure that arises during the fabrication process is studied by considering its implications in the propagation loss based on the Rayleigh-Mie scattering loss mechanism. We demonstrate that the porous structure is to be reduced to the nanoscale (i.e., <10 nm) to realize waveguide structures with ultra-low propagation losses based on fabrications and measurements of morphologies with various degrees of porosity. Further, the bending loss and its respective polarization-dependent propagation loss behavior are analyzed to realize compact devices with ultra-low-loss and polarization-independent features, where a 4 mm bending radius is found to be adequate for such a performance over the 1550 nm band.

Influence of dispersion properties of the delay line in self heterodyne linewidth measurements

We report experimental results of the influence of 1/f noise on the laser linewidth measurements using the self heterodyne technique and suggest a method of isolating it from the dispersive broadening caused by the delay line in the interferometer.