Ultracompact and wideband power splitter based on triple photonic crystal waveguides directional coupler

Real-Time Tunable Optofluidic Splitter via Two Laminar Flow Streams in a Microchannel

This paper reports a tunable optofluidic splitter in which the incident light is split via refraction and reflection at the interface between two laminar flows in a microchannel but with different refractive indices. A Y-junction microchannel is used to demonstrate the continuous tuning of the splitting ratio of optical power by smooth adjustment of the ratio of two flow rates. In addition, it has achieved the tuning of split angle from 5° to 19° by the control of the refractive index contrast. The dynamic response gives a fastest switching frequency of 1.67 Hz between the "wave-guiding" and "splitting" status.

A Broadband Terahertz Waveguide T-Junction Variable Power Splitter

In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.

Finite element method analysis of band gap and transmission of two-dimensional metallic photonic crystals at terahertz frequencies

Photonic band gap and transmission characteristics of 2D metallic photonic crystals at THz frequencies have been investigated using finite element method (FEM). Photonic crystals composed of metallic rods in air, in square and triangular lattice arrangements, are considered for transverse electric and transverse magnetic polarizations. The modes and band gap characteristics of metallic photonic crystal structure are investigated by solving the eigenvalue problem over a unit cell of the lattice using periodic boundary conditions. A photonic band gap diagram of dielectric photonic crystal in square lattice array is also considered and compared with well-known plane wave expansion results verifying our FEM approach. The photonic band gap designs for both dielectric and metallic photonic crystals are consistent with previous studies obtained by different methods. Perfect match is obtained between photonic band gap diagrams and transmission spectra of corresponding lattice structure.

Direct slow-light excitation in photonic crystal waveguides forming ultra-compact splitters

Based on a series of 1x2 beam splitters, novel direct excitation of slow-light from input- to output-region in photonic crystal waveguides is investigated theoretically and experimentally. The study shows that the slow-light excitation provides over 50 nm bandwidth for TE-polarized light splitting between two output ports, and co-exists together with self-imaging leading to ~20 nm extra bandwidth. The intensity of the direct excitation is qualitatively explained by the overlap integral of the magnetic fields between the ground input- and excited output-modes. The direct excitation of slow light is practically lossless compared with transmission in a W1 photonic crystal waveguides, which broadens the application-field for slow-light and further minimizes the size of a 1x2 splitter.

1x3 beam splitter for TE polarization based on self-imaging phenomena in photonic crystal waveguides

Based on inspiration from multi-mode interference self-imaging and theoretical FDTD simulations, a 1x3 beam splitter was designed, fabricated and characterized. Measurements show that for TE-polarized incident light the power is distributed equally between the output ports within 1dB in the range from 1541nm to 1552nm, and the total transmission of the 1x3 splitter is equal to the corresponding length of a single-line-defect PhCW within the measurement uncertainty.

Power splitters with different output power levels based on directional coupling

The properties of a wideband photonic crystal power splitter with different output power levels based on directional coupling are investigated numerically with the finite-difference time-domain method. The effects of changing the coupling length and radius of the coupling rods between parallel waveguides on output transmissions are investigated. By further splitting power in each branch a power splitter with four output branches is proposed.

Ultracompact photonic coupling splitters twisted by PTT nanowires

We report a series of ultracompact photonic coupling splitters with multi-input/output ports assembled by twisting flexible polymer nanowires, which were fabricated by one-step drawing method from poly(trimethylene terephthalate) (PTT). Experimental demonstration shows that the properties of the splitters are dependent on the operation wavelength and the input branch of the optical signal launched. For a fixed operation wavelength and the input branch, desirable splitting ratio can be tuned by controlling the input/output branching angle. The excess loss of these splitters is less than 1 dB, and the intrinsic loss is less than 0.4 dB. They are desirable for high density photonic integrated circuits (PICs) and nanonetworks, while the twisting technology will be useful in constructing other wire-based photonic devices.