Academic literature on the topic 'Silicon microring resonators'

Silicon photonics is a very promising technology for future low-cost high-bandwidth optical telecommunication applications down to the chip level. This is due to the high degree of integration, high optical bandwidth and large speed coupled with the development of a wide range of integrated optical functions. Silicon-based microring resonators are a key building block that can be used to realize many optical functions such as switching, multiplexing, demultiplaxing and detection of optical wave. The ability to tune the resonances of the microring resonators is highly desirable in many of their applications. In this work, the study and application of a thermally wavelength-tunable photonic switch based on silicon microring resonator is presented. Devices with 10µm diameter were systematically studied and used in the design. Its resonance wavelength was tuned by thermally induced refractive index change using a designed local micro-heater. While thermo-optic tuning has moderate speed compared with electro-optic and all-optic tuning, with silicon’s high thermo-optic coefficient, a much wider wavelength tunable range can be realized. The device design was verified and optimized by optical and thermal simulations. The fabrication and characterization of the device was also implemented. The microring resonator has a measured FSR of ~18 nm, FWHM in the range 0.1-0.2 nm and Q around 10,000. A wide tunable range (>6.4 nm) was achieved with the switch, which enables dense wavelength division multiplexing (DWDM) with a channel space of 0.2nm. The time response of the switch was tested on the order of 10 us with a low power consumption of ~11.9mW/nm. The measured results are in agreement with the simulations. Important applications using the tunable photonic switch were demonstrated in this work. 1×4 and 4×4 reconfigurable photonic switch were implemented by using multiple switches with a common bus waveguide. The results suggest the feasibility of on-chip DWDM for the development of large-scale integrated photonics. Using the tunable switch for output wavelength control, a fiber laser was demonstrated with Erbium-doped fiber amplifier as the gain media. For the first time, this approach integrated on-chip silicon photonic wavelength control.

Photonic sensing technologies offer unexceptionable features for taking high requirement measurement in a harsh environment. They inherit advantages such as fast speed and immunity from electromagnetic interference from optical communications. In addition, with the silicon-on-insulator (SOI) technologies, chip scale optical sensors are capable of providing high sensitivity with an ultra-compact form factor. The motivation is derived from the high demand for sensors in the new era of the Data Age and the great potential of fast response, highly sensitive and ultra-compact photonic sensor. Furthermore, rapid sensor development puts forward a new prospect for many areas such as medical and health measurement, defence technology, and the internet of things. With all the advantages that SOI-based chip scale optical sensors provide, there are still shortcomings can be improving to provided much more capable sensing abilities from many aspects. With that in mind, this thesis will focus on SOI-based optical microring resonator, one of the most popular SOI-based optical structure for sensing purpose; and solutions for two shortcomings of the common SOI-based optical sensor. One of the solutions that will be mentioned in this thesis is intended to solve the issues of limited measurement speed and low resolution that caused by the way of the data analysis in the common SOI-based optical sensing system. The second purposed solutions in this thesis focused on the connection schemes of the SOI-based optical sensor; Common connection schemes of SOI-based optical chip needs at least two optical ports for coupling the light into and out of the silicon photonics chip which limits the ability to perform measurements at remote locations that are hard to be reached. Chapter 4 and 5 of this thesis contains detailed explorations of these shortcomings and solutions. An integrated photonic sensor based on optoelectronic oscillator with an on-chip sensing probe that is capable of realising highly sensitive and high-resolution optical sensing is presented in this thesis as a solution for the first shortcoming. The key component is an integrated SOI-based microring resonator which is used to implement a microwave photonic bandpass filter (MPBF) to effectively suppress the side modes of the optoelectronic oscillator (OEO) by more than 30dB, thus generating a peak RF signal that maps the detected optical change into a resulting shift in the oscillating frequency. As an application example, the proposed optical sensor system is employed to detect small changes in temperature, and experimental results demonstrate a highly sensitive optical temperature sensor with an achieved sensitivity of 7.7 GHz/°C. Moreover, the proposed sensing system revealed a 0.02°C measurement resolution which is a tenfold improvement compared with the modest resolution of 0.23°C seen by the conventional MPBF system without the OEO loop, rendering it highly suitable for diverse high-resolution sensing applications. With the purpose of reducing the size of the SOI-based photonic sensor and to overcoming the second shortcoming, an ultra-compact, reflective optical sensor probe based on SOI microring resonator and Y-junction structure is also presented in this thesis. This structure is capable of simultaneously achieving high sensitivity and fine resolution optical sensing. The reflective configuration of the probe enables remote measurements at locations which are otherwise hard to be assessed by transmission based sensors. As an application example, the proposed sensor probe for temperature measurement is demonstrated. Experiment results show that the center wavelength shift of the sensor’s reflected spectrum offers a linear response to temperature change with a high sensitivity of 66 pm/°C.

The experimental work that is reported in the thesis explores some properties and possible uses of silicon microring resonators as integrated sources of non-classical states of light, based on the enhancement of non-linear effect of four-wave mixing (FWM).<br>The experimental work that is reported in the thesis explores some properties and possible uses of silicon microring resonators as integrated sources of non-classical states of light, based on the enhancement of non-linear effect of four-wave mixing (FWM).

The objective of this work is to develop essential building blocks for the lab-on-a-chip optical sensing systems with high performance. In this study, the silicon-on-insulator (SOI) platform is chosen because of its compatibility with the mature microelectronics industry for the great potential in terms of powerful data processing and massive production. Despite the impressing progress in optical sensors based on the silicon photonic technologies, two constant challenges are larger sensitivity and better selectivity. To address the first issue, we incorporate porous materials to the silicon photonics platform. Two porous materials are investigated: porous silicon and porous titania. The demonstrated travelling-wave resonators with the magnesiothermically reacted porous silicon cladding have shown significant enhancement in the sensitivity. The process is then further optimized by replacing the thermal oxide with a flowable oxide for the magnesiothermic reduction. A different approach of making porous silicon using porous anodized alumina membrane leads to better flexibility in controlling the pore size and porosity. Porous titania is successfully integrated with silicon nitride resonators. To improve the selectivity, an array of integrated optical sensors are coated with different polymers, such that each incoming gas analyte has its own signature in the collective response matrix. A multiplexed gas sensor with four polymers has been demonstrated. It also includes on chip references compensating for the adverse environmental effects. On chip spectral analysis is also very critical for lab-on-a-chip sensing systems. For that matter, based on an array of microdonut resonators, we demonstrate an 81 channel microspectrometer. The demonstrated spectrometer leads to a high spectral resolution of 0.6 nm, and a large operating bandwidth of ~ 50 nm.