ABSTRACT
We present an optimization of spot-size converter (SSC) of waveguide photodetector (PD) for small polarization dependent loss (PDL). Beam-propagation method simulation gives responsivity for each polarization and SSC structure. From the calculated responsivity data, optimum structure of SSC is determined that can be implemented with a sufficient process tolerance. We confirm the optimization by measuring PDL of waveguide PD designed according to the structure obtained through the simulation.
Subject(s)
Photometry/instrumentation , Refractometry/instrumentation , Surface Plasmon Resonance/instrumentation , Computer Simulation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Models, TheoreticalABSTRACT
We propose and demonstrate the use of subcarrier/polarization-interleaved training symbols for channel estimation and synchronization in polarization-division multiplexed (PDM) coherent optical orthogonal frequency-division multiplexed (CO-OFDM) transmission. The principle, the computational efficiency, and the frequency-offset tolerance of the proposed method are described. We show that the use of subcarrier/polarization interleaving doubles the tolerance to the frequency offset between the transmit laser and the receiver's optical local oscillator as compared to conventional schemes. Using this method, we demonstrate 43-Gb/s PDM CO-OFDM transmission with 16-QAM subcarrier modulation over 5,200-km of ultra-large-area fiber.
ABSTRACT
We show that the temperature dependence of a silicon waveguide can be controlled well by using a slot waveguide structure filled with a polymer material. Without a slot, the amount of temperature-dependent wavelength shift for TE mode of a silicon waveguide ring resonator is very slightly reduced from 77 pm/ degrees C to 66 pm/ degrees C by using a polymer (WIR30-490) upper cladding instead of air upper cladding. With a slot filled with the same polymer, however, the reduction of the temperature dependence is improved by a pronounced amount and can be controlled down to -2 pm/ degrees C by adjusting several variables of the slot structure, such as the width of the slot between the pair of silicon wires, the width of the silicon wire pair, and the height of the silicon slab in our experiment. This measurement proves that a reduction in temperature dependence can be improved about 8 times more by using the slot structure.
