| dc.description.abstract | In the communications field, the need for high-speed transport and large-bandwidth data communication is increasing rapidly. Comparing to the copper conductor in electrical communication, the optical waveguide provides higher speed, wider bandwidth, and lower loss. Thus, the application of silicon photonics become a good candidate for the next generation communication. The basic operation system includes photonics circuit for communication and electronics circuit for computation. The electrical signal is converted into optical signal by modulating either the intensity or the phase of a laser. Then, the optical signal is transported by the optical fiber externally and the optical waveguide internally. For the receiver, the optical signal is converted back into electrical signal by an optical receiver. Besides, for high-power optical sources, there are significant applications in various domains including optical amplifiers, Raman lasers, medicine, and spectroscopy. Recently, these studies have been investigated in on-chip systems, especially for generating optical nonlinear signals.
To study optical nonlinearity, high optical power is a must. However, during the measurement of optical fibers coupling to waveguides with high input power, the mechanical vibration of the optical fiber would be a critical problem for coupling stability. Traditionally, it can be compromised by fabricating either V- or U-Groove structures. U-Groove was first made in the off-chip type. As the demands for photonics increase, U-Groove is gradually developed into the on-chip type. In the past, these on-chip U-Grooves are widely used and patterned after the waveguide formation. In this thesis, we present a new fabrication process, Groove-first, which U-Grooves were formed before the waveguide formation. Groove-first process can solve the problem of silicon nitride film stress by combining the strain-relaxed pattern during U-Groove formation. Also, this process can prevent the etching of silicon oxide and mass produce U-Groove chips. In terms of waveguide, unwanted process onto the waveguide structure can be avoided. The natural inverse taper waveguide can be formed by MA6 which break its resolution limit.
In the first part of this thesis, we will discuss the fabrication and process optimization of U-grooves before patterning the waveguide. Second, silicon nitride-based waveguides were chosen to be the photonic platform for fiber-waveguide interconnection. Last, we will show that the measurement error caused by the mechanical vibration could be released comparing to the traditional coupling without the grooves and the power variation is found to be below 10% even with the input power up to 800mW. | en_US |