Output Transmission Efficiency Research Articles

Ultra-broadband and low-loss 3 dB optical power splitter based on adiabatic tapered silicon waveguides.

A broadband, low-loss and polarization-insensitive 3 dB optical power splitter based on adiabatic tapered silicon waveguides is proposed and investigated. 3D-FDTD simulation results show that the splitter achieves an output transmission efficiency of nearly 50% over an ultra-broad wavelength range from 1200 to 1700 nm. The device is fabricated, and experimental results show that the splitter exhibits a low excess loss of <0.19 dB for the TE polarization and <0.14 dB for the TM polarization over the entire measured wavelength range from 1530 to 1600 nm, while having an adiabatic taper length of only 5 μm. In addition, the measured power uniformity of the cascaded 1×8 splitter is only 0.47 dB, and 0.17 dB for the TE and TM polarizations, respectively. With the advantages of low loss, broad bandwidth, and compact size, the proposed splitter is a promising element for large-scale silicon integrated photonic circuits.

Design of Photonic Crystal Triplexer with Core-Shell Rod Defects

We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are created by introducing air holes in the center of the silicon rods. By varying the radii of the air holes, three specific wavelengths 1.31, 1.49 and 1.55 μm can be obtained. This structure is designed and its performance is verified by the finite-difference time-domain method, which is highly suitable for photonic integrated circuits (PICs). The average output transmission efficiency and quality factor are more than 98.85% and 560, respectively. The mean value of the crosstalk between output channels is about −36.49 dB. The present device is extremely compact with total size 96.24 μm2, which is suitable for PICs and can be utilized in the fiber-to-the-home system.

2D MEMS electrostatic cantilever waveguide scanner for potential image display application

This paper presents the current status of our micro-fabricated SU-8 2D electrostatic cantilever waveguide scanner. The current design utilizes a monolithically integrated electrostatic push-pull actuator. A 4.0 μm SU-8 rib waveguide design allows a relatively large core cross section (4μm in height and 20 μm in width) to couple with existing optical fiber and a broad band single mode operation (λ= 0.7μm to 1.3μm) with minimal transmission loss (85% to 87% output transmission efficiency with Gaussian beam profile input). A 2D scanning motion has been successfully demonstrated with two fundamental resonances found at 202 and 536 Hz in vertical and horizontal directions. A 130 μm and 19 μm, corresponding displacement and 0.062 and 0.009 rad field of view were observed at a +150V input. Beam divergence from the waveguide was corrected by a focusing GRIN lens and a 5mm beam diameter is observed at the focal plane. The transmission efficiency is low (~10%) and cantilever is slightly under tensile residual stress due to inherent imperfection in the process and tooling in fabrication. However, 2D light scanning pattern was successfully demonstrated using 1-D push-pull actuation.

High-Transmission-Efficiency 120 &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$^{\circ}$&lt;/tex-math&gt;&lt;/inline-formula&gt; Photonic Crystal Waveguide Bend by Using Flexible Structural Defects

We numerically studied a high-output-transmission-efficiency low-reflection-loss 120° photonic crystal (PhC) waveguide bend based on a PhC slab with triangular-lattice air holes. The desired high output transmission efficiency was achieved by introducing flexible structural defects into the bend region of the waveguide. Simulation results obtained using a 3-D finite-difference time-domain method indicated that normalized output transmission as high as 94.3% and negligible normalized reflection loss of 0.1% were obtained at the 1550-nm optical wavelength. Furthermore, the normalized output transmission was more than 90% within the entire optical C-band. In addition, sensitivity of the design parameters of the structural defect was studied to understand the tolerance in the fabrication error, while maintaining high output transmission efficiency.

MEMS Based Mechanical Resonant Push-Pull Scanning Endoscope

Here we present a microfabricated SU-8 cantilever scanner. Current SU-8 rib waveguide design improved the output beam diameter of our previous design from ~50μm to ~5.0μm, further improves our spatial resolution. The proposed rib waveguide design also allows a relatively large waveguide cross section (4μm in height and 55μm in width) and broader wavelength range in single-mode operation (λ= 0.7μm to 1.3μm) with a minimum transmission loss (85% output transmission efficiency with Gaussian beam profile input). Our design also provides a new means to create a 2-D raster scanning pattern using a microfabricated push-pull actuator, verified by a transient finite element analysis (FEA). The scanner's line resolution and field of view (FOV) have been optimized through a parametric study using modal and harmonic analyses. This optical scanner may find application in the area of endoscopy, where there is a need for a minimally invasive device that reduces patient discomfort.