Photonic microwave or millimeter wave (MMW) sources that produce highly stable and broadly tunable microwave frequencies of low phase noise are anticipated for many applications ranging from broadband wireless access networks and satellite communication systems to emerging broadband photonics-based phased-array antennas and radars.

The goal of this dissertation is to investigate and control the characteristics of the generated photonic microwave frequencies induced by an optically injected semiconductor laser. Two ways of controlling the dynamics are considered: through the control of the operational parameters of the optically injected laser system and through the control of the intrinsic parameters of the injected semiconductor laser. Controlling the operating parameters shows limit cycles of period one (P1) and period two (P2) that have reduced sensitivity to intrinsic laser noise and small-signal fluctuations in the operating conditions. The intrinsic parameters of the semiconductor laser, particularly the gain saturation factor, are shown to have significant effects on the characteristics of the nonlinear dynamics in both the stable-locking and periodic regions. Therefore, this dissertation shows the optimal operating points of the optically injected semiconductor laser for photonic microwave applications.

In this thesis, we focus on graphene-based surface plasmon-polaritons at terahertz frequencies and their possible applications. The primary motivation is to efficiently couple free-space terahertz radiation into an ultra-compact and low-loss waveguide. Characteristics of surface plasmon-polaritons on monolayer and double-layer graphene are first re-derived and reviewed. Then we propose two novel waveguide structures: graphene-metal structure and graphene-wrapped fibers. Possible modes that can be supported by the structures are analyzed and how to excite them is addressed. Also, promising applications are briefly described. Our work reveals that graphene-metal structure is a good starting point for exploration of both new physics and innovative devices, and that graphene-wrapped fibers can also be of substantial interest as the quality of graphene is improved.

Sluicing is a type of ellipsis where only a wh-phrase, the remnant, is pronounced while the entire TP node of the embedded interrogative clause is unpronounced (e.g. ‘John met someone, but I don’t know who’). Traditional analyses of sluicing (Ross 1969, Merchant 2001) involve wh-movement of the remnant, followed by the deletion of TP (e.g. ‘John met someone yesterday, but I don’t know who John met yesterday’). The remnant is taken to move overtly in a similar fashion to regular wh-words in questions. This dissertation argues against wh-movement in sluicing and proposes an alternative analysis that does not involve overt movement of the remnant. The analysis is explored with Malay (Austronesian, Malaysia), which has both movement and no movement for question formation. Evidence from Malay suggests that sluicing uses the no movement option rather than the movement option for sluicing. In the proposed analysis, the remnant does not move, while the surrounding material is elided (e.g. ‘John met someone yesterday, but I don‘t know John met who yesterday’). The remnant is argued to have the semantic characteristics of in situ wh-phrases and indefinites, both of which do not undergo movement. These characteristics are argued to give rise to the patterns seen in sluicing. This analysis is then implemented within the Minimalist Grammars framework, where the architecture of the grammar allows for the possibility of non-constituent deletion. Movement in Minimalist Grammars is thought to involve multi-component expressions that allows individual components to be held out of the main derivation. The analysis makes use of this notion of separation between components to implement sluicing.

Nonlinear dynamics of semiconductor lasers is applied for microwave frequency division. Optical injection is used to drive a slave laser into the dynamical period-two state. A fundamental microwave frequency and its suhharmonic are generated in the power spectrum. Both frequencies will be simultaneously locked when an external microwave near either frequency is applied on the bias. In our experiment, precise microwave frequency division is demonstrated by modulating the laser at the fundamental of 18.56 GHz. A locked subharmonic at 9.28 GHz with a low phase variance of 0.007 rad(2) is obtained from a 10-dBm input. A large locking range of 0.61 GHz is measured under a 4-dBm modulation. Similarly, precise frequency multiplication is demonstrated by modulating at 9.65 GHz. At an input power of -5 dBm, a multiplied signal at 19.30 GHz is obtained with a phase variance of 0.027 rad(2) and a locking range of 0.22 GHz.

Analysis of the limit-cycle, also known as period-one (P1), dynamics induced by strong optical injection to a semiconductor laser is carried out. Based on the well-established laser rate equations, an approximate solution of the P1 dynamics can be obtained by starting with a general limit-cycle solution. Our results are in good agreement with numerical and experimental results by taking the second harmonic of the P1 frequency into account. Our analysis shows that the strong coupling between the oscillating carrier density and the oscillating optical field is responsible for the high nonlinearity of these P1 dynamics.

Nonlinear dynamics of an optically injected semiconductor laser is applied to photonic microwave generation. By properly adjusting the injection conditions, the optical frequency of the slave laser is first locked to the master laser. The slave laser is then driven into a periodic dynamical state, resulting in a single-sideband (SSB) microwave modulation on the optical carrier. The frequency of the SSB can be controlled by the optical injection strength and detuning. Frequency-modulated SSB can, thus, be obtained from a modulated injection. In this work, we experimentally investigate the generated SSB in terms of its broad tunability and fast modulation response. The results suggest application of this system in radio-over-fiber and optical subcarrier multiplexing technologies when microwave frequency modulation or frequency-shift keying is employed.

Graphene is a one-atom-thick 2D system that has a unique hexagonal crystal structure of two carbon atoms per unit cell. Unlike any other 2D semiconductor material known today, intrinsic graphene has a zero bandgap with its charged carriers behaving like Dirac fermions with a zero mass, resulting in many extraordinary properties that are very different from other materials. Such properties can be controllably modified by proper impurity doping or by electrical or optical modulation, making graphene extremely attractive for novel device applications. The salient electronic, optical, and optoelectronic properties of graphene, together with its unique nanostructure, offer innovative opportunities to many potentially revolutionary applications for high-speed/high-frequency electronic and optoelectronic devices, terahertz (THz) oscillators and sensors, and ultrafast nonlinear optical elements. Realization of these exciting graphene-based devices, as well as the possibility for further innovation, relies on a good understanding of graphene’s electronic, optical and optoelectronic properties in the broad spectral range from THz to the visible. In this thesis, the electronic property of graphene is investigated first, followed by the discussion of THz property of graphene. Based on the derived models of the electronic and THz properties of graphene, we can describe the plasmonic behavior of graphene in various configurations, such as graphene-based THz waveguide. A concept THz device is demonstrated both theoretically and experimentally in the last.

In this thesis, two models are developed to describe the optical properties of graphene from the THz to the visible spectral region. We show that the optical conductivity is mainly contributed by interband carrier transitions in the visible region and by intraband carrier scattering in the THz range. Optical properties such as refractive index and transmittance can be calculated theoretically from the model in the optical range. In the THz range, the Fermi energy and the scattering rate are two important parameters in the determination of the optical conductivity. One can use these physical quantities as fitting parameters and find their values by fitting the THz model to the experimental data. The fitted results are consistent with the data and one can predict the optical conductivity and refractive index at the frequency higher than the bandwidth of our experiments. Other physical properties such as the carrier density and the mobility can also be obtained from the fitted parameters. The resultant mobilities of monolayer graphene and bilayer graphene are consistent with the results of other groups.