We demonstrate a high bit-rate optical signal transmission by using long-range surface plasmon polariton (LRSPP) waves in a guided geometry. With a $40\mathrm{Gbit}∕\mathrm{s}$ optical communication signal, eye patterns and bit-error-rates were measured to access the quality of the transmission properties of the LRSPP mode. A thin gold strip line embedded in a low loss optical polymer supports a LRSPP mode, which propagates with a $2\mathrm{dB}∕\mathrm{cm}$ loss, and couples to standard single mode fibers at $1.55\mu \mathrm{m}$ with a $2\mathrm{dB}$ coupling loss. A $40\mathrm{Gbit}∕\mathrm{s}$ optical signal was transmitted via a $4\mathrm{cm}$ long LRSPP waveguide without any distortion of the eye patterns. The experiment also showed error-free transmissions. These results indicate that the LRSPP waveguide is a potential transmission line for optical interconnections overcoming the inherent problems in electric interconnections.

To improve the propagation loss of polymer-based long-range surface-plasmon-polariton (LR-SPP) waveguide devices at the telecom wavelength range, low-loss LR-SPP waveguides were fabricated in an ultraviolet-curable acrylate polymer with a low refractive index and absorption loss. A propagation loss of 1.72 dB/cm at a wavelength of 1.55 mum was achieved with a 14-nm-thick and 3-mum-wide metal stripe.

We demonstrate sub-dB/cm propagation losses in polymer-based silver stripe waveguides at the wavelength of 1.31 μm. The silver stripe waveguides were fabricated in a low-loss fluorinated polymer clad. To form uniform metal stripe patterns, which are essential for reducing propagation loss, we developed a lift-off process using double layers of photoresist and SiN_x. A propagation loss of less than 1.0 dB/cm was obtained with the 11-nm-thick silver stripes in the width range of 1.5 - 4.5 μm. A coupling loss of ~1.0 dB with a polarization maintaining single mode fiber was achieved for a width of 4.5 μm. For a width of 2.0 μm, we recorded a minimum propagation loss of 0.4 dB/cm, which is comparable with that of dielectric multi-mode waveguides.

We present what we believe to be a novel high-efficiency photonic crystal polarization beam splitter that consists of a polarizing photonic crystal slab embedded in a two-dimensional self-collimating square lattice photonic crystal of air holes in silicon. The polarizing photonic crystal slab with the same lattice constant as the self-collimating photonic crystal background exhibits not only high reflection for transverse electric (TE) and high transmission for transverse magnetic (TM) polarization, but also high extinction ratios for both two-polarization output channels. Moreover, high-efficiency common antireflection structures for both TE and TM polarizations are applied at the input and output ends of the photonic crystal polarization beam splitter, thereby enabling one to achieve a highly efficient photonic crystal polarization beam splitter. It is shown that the primary transmissions exceeding 94.04% for TE and 92.39% for TM polarization output channels are achieved through the proposed photonic crystal polarization beam splitter.

We present characteristics of very thin Au strip waveguides based on long-range surface plasmon polaritons (LR-SPPs) along thin Au strips embedded in polymers. We also report a 10 Gbps optical signal transmission via LR-SPPs with the pig-tailed Au strip waveguide at a telecommunication wavelength of 1.55 mum. We limited the thickness, width, and length up to ~20 nm, ~ 10 mum, and ~5 cm, respectively, for practical applications. At 1.55 mum, loss properties of the Au strip waveguides were theoretically and experimentally evaluated with thickness, width and cladding material. The lowest propagation loss of ~1.4 dB/cm was experimentally obtained with the 14-nm-thick and 2-mum-wide Au strip. With a single-mode fiber, the lowest coupling loss of less than 0.1 dB/facet was achieved with the 14-nm-thick and 7.5-mum-wide Au strip. The lowest insertion loss was obtained 7.7 dB with the 14-nm-thick, 5-mum-wide, and 1.5-cm-long Au strip. The propagation loss was improved approximately 30% for the 17-nm-thick Au strip with lowering the refractive index of the cladding polymer by 0.01. In the 10 Gbps optical signal transmission experiment, the LR-SPP waveguide exhibits an excellent eye opening and a 2.2 dB power penalty at 10^-12 bit error rate. These all results indicate that the LR-SPP waveguide is a potential transmission line for optical interconnects to overcome inherent problems in electric interconnects.

We present a high-efficiency antireflection structure for both TE and TM polarizations in two-dimensional self-collimating square lattice photonic crystal consisting of air holes in silicon. The design parameters of the optimal antireflection structure can be obtained by using the concept of Fresnel coefficients and the finite-difference time-domain simulations. The photonic crystal operating in almost identical self-collimation frequencies for two polarizations exhibits a large reflection coefficient for TE and a very small one for TM polarization. In this case, the antireflection structure for TE can also improve the transmission for TM polarization. To confirm a highly efficient antireflection structure designed, we investigate the transmission data of three finite photonic crystal samples consisting of 36, 38 and 40 unit cells for the cases without and with the antireflection structures through finite-difference time-domain simulations.