C. H. Yeh

A comparison of slurry erosion characteristics of TiNi shape memory alloys and SUS304 stainless steel

Abstract The slurry erosion characteristics of three TiNi shape memory alloys and SUS304 stainless steel using the liquid/solid impingement have been systematically studied. Experimental results show that more resistant TiNi alloys and less resistant SUS304 stainless steel exhibit ductile behavior and the maximum erosion has observed at 30°. The surface morphologies exhibit many long furrows and ridges at low impingement angles. The exponent in the relation e = kV n varied between 2 and 3 for impingement angles between 15° and 90°. Work hardening of surface is observed on the surface of all tested materials. The work hardening layer and thin platelet formation increase with angle of impingement. The SIM formation and pseudoelastic behavior of TiNi B2 phase, and variant accommodation and SIP formation of TiNi martensite, make important contributions to the slurry erosion resistance of TiNi alloys.

Equalization of PAM-4 Signal Generated by Silicon Microring Modulator for 64-Gbit/s Transmission

We propose and demonstrate a 64-Gbit/s four-level pulse-amplitude-modulation transmission by using a limited modulation bandwidth silicon microring modulator (SiMRM) and the Volterra equalization scheme. Severe intersymbol interference caused by both the chromatic dispersion of the optical fiber and the bandwidth limitation of components can be compensated. Besides, several equalization schemes are compared and analyzed in terms of performance and complexity. In addition, the design and characteristics of the SiMRM used in the experiment are also discussed.

Utilizing new erbium-doped fiber laser scheme for long-distance fiber Bragg grating (FBG) sensor system

We propose and demonstrate a new erbium-doped fiber (EDF) ring laser structure for 10 km long fiber sensor application. Here, we utilize ten fiber Bragg gratings (FBGs) as fiber sensors for sensing strain change. In the experiment, we can tune the passband of tunable bandpass filter (TBF) inside a fiber ring cavity to match the Bragg wavelength of each FBG to lase corresponding wavelength. Hence, the temperature-induced shift in Bragg wavelength could be monitored. In addition, 10 km long distance single-mode fiber (SMF) can be achieved by using the proposed EDF ring laser scheme for FGB-based remote sensor system.

Wavelength-tunable erbium-doped fiber laser using silicon-on-insulator (SOI) based micro-ring with narrow laser linewidth

We propose and demonstrate a wavelength-tunable and narrow-linewidth erbium-doped fiber (EDF) laser using siliconon- insulator (SOI) based micro-ring. We discuss the wavelength selection and wavelength-tunable operation of the proposed fiber laser. The SOI based micro-ring is fabricated on a SOI wafer with a 0.22 um thick top silicon layer and a 2 um thick burial oxide (BOX) layer. In order to enhance the coupling efficiency between the SOI based micro-ring and the EDF, a pair of uniform period grating couplers are used. In the experiment, the lasing wavelengths can be tuned in the wavelengths range from 1532 nm to 1567.2 nm with a tuning step of 2 nm. The wavelength range and the tuning step are determined by the EDFA gain-bandwidth and the FSR of the SOI based micro-ring respectively. The OSNR of each lasing wavelength is > 42 dB. By using a double-ring configuration, a narrow laser linewidth of 50 kHz can be achieved.

Low bending loss square-core optical fiber for optical communication

In this work, we propose and demonstrate a single-mode square-core optical fiber for optical communications. In the proposed square-core single-mode-fiber (SC-SMF), high bandwidth-distance product and low bending loss can be achieved. In this paper, first of all, we discuss the single mode condition of the SC-SMF theoretically and numerically. Then, we discuss the fabrication of the SC-SMF. We also characterize the performances of the proposed SC-SMF, such as the bending loss, and compare it with the standard single mode fiber (SSMF). A 10 Gb/s transmission experiment using 200 m, 500 m and 1 km SC-SMFs are performed. Negligible power penalty is observed.