1.55-[micrometer] high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed ([greater than]5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (~ 3 MHz), the relative intensity noise (RIN) ([less than]-150 dB/Hz), as well as the modal RIN (~ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system.

THis book shows you the principles of operation, device structure, noise properties, and a wide range of possible application systems of semiconductor lasers, and describes methods for improving their coherence. Supported by 300 equations and 169 illustrations.

This book provides guidelines and design rules for developing high-performance, low-cost, and energy-efficient quantum-dot (QD) lasers for silicon photonic integrated circuits (PIC), optical frequency comb generation, and quantum information systems. To this end, the nonlinear properties and dynamics of QD lasers on silicon are investigated in depth by both theoretical analysis and experiment. This book aims at addressing four issues encountered in developing silicon PIC: 1) The instability of laser emission caused by the chip-scale back-reflection. During photonic integration, the chip-scale back-reflection is usually responsible for the generation of severe instability (i.e., coherence collapse) from the on-chip source. As a consequence, the transmission performance of the chip could be largely degraded. To overcome this issue, we investigate the nonlinear properties and dynamics of QD laser on Si in this book to understand how can it be applied to isolator-free photonic integration in which the expensive optical isolator can be avoided. Results show that the QD laser exhibits a high degree of tolerance for chip-scale back-reflections in absence of any instability, which is a promising solution for isolator-free applications. 2) The degradation of laser performance at a high operating temperature. In this era of Internet-of-Thing (IoT), about 40% of energy is consumed for cooling in the data center. In this context, it is important to develop a high-temperature continuous-wave (CW) emitted laser source. In this book, we introduce a single-mode distributed feedback (DFB) QD laser with a design of optical wavelength detuning (OWD). By taking advantage of the OWD technique and the high-performance QD with high thermal stability, all the static and dynamical performances of the QD device are improved when the operating temperature is high. This study paves the way for developing uncooled and isolator-free PIC. 3) The limited phase noise level and optical bandwidth of the laser are the bottlenecks for further increasing the transmission capacity. To improve the transmission capacity and meet the requirement of the next generation of high-speed optical communication, we introduce the QD-based optical frequency comb (OFC) laser in this book. Benefiting from the gain broadening effect and the low-noise properties of QD, the OFC laser is realized with high optical bandwidth and low phase noise. We also provide approaches to further improve the laser performance, including the external optical feedback and the optical injection. 4) Platform with rich optical nonlinearities is highly desired by future integrated quantum technologies. In this book, we investigate the nonlinear properties and four-wave mixing (FWM) of QD laser on Si. This study reveals that the FWM efficiency of QD laser is more than ten times higher than that of quantum-well laser, which gives insight into developing a QD-based silicon platform for quantum states of light generation. Based on the results in this book, scientists, researchers, and engineers can come up with an informed judgment in utilizing the QD laser for applications ranging from classical silicon PIC to integrated quantum technologies.

This book provides a comprehensive overview of the state-of-the-art in the development of semiconductor nanostructures and nanophotonic devices. It covers epitaxial growth processes for GaAs- and GaN-based quantum dots and quantum wells, describes the fundamental optical, electronic, and vibronic properties of nanomaterials, and addresses the design and realization of various nanophotonic devices. These include energy-efficient and high-speed vertical cavity surface emitting lasers (VCSELs) and ultra-small metal-cavity nano-lasers for applications in multi-terabus systems; silicon photonic I/O engines based on the hybrid integration of VCSELs for highly efficient chip-to-chip communication; electrically driven quantum key systems based on q-bit and entangled photon emitters and their implementation in real information networks; and AlGaN-based deep UV laser diodes for applications in medical diagnostics, gas sensing, spectroscopy, and 3D printing. The experimental results are accompanied by reviews of theoretical models that describe nanophotonic devices and their base materials. The book details how optical transitions in the active materials, such as semiconductor quantum dots and quantum wells, can be described using a quantum approach to the dynamics of solid-state electrons under quantum confinement and their interaction with phonons, as well as their external pumping by electrical currents. With its broad and detailed scope, this book is indeed a cutting-edge resource for researchers, engineers and graduate-level students in the area of semiconductor materials, optoelectronic devices and photonic systems.

Semiconductor lasers have been one of the major building blocks of fiber-optics based communication systems. For the past two decades, specifications of these lasers have been tailored to particular applications by defining certain performance parameters that do not necessarily overlap from one application to another. In order to commoditize laser sources by increasing volume and reducing cost, the laser performance parameters needed to be generic and not customized. In this simulation work, we modify and enhance essential performance parameters of a simple, low-cost laser with generic specifications and tailor it to specific applications that normally require advanced and complicated laser structures, by using electronic feedback for instantaneous impairment correction, while at the same time maintain a compact size for the laser and the supporting circuitry around it. We essentially use the same laser chip to cover the three distinct applications being analyzed. Maintaining generic laser chip specifications while only modifying the feedback loop circuit design parameters can facilitate photonic hybrid integration. Specific applications targeted are, linear optical-analog transmission for wireless backhauling by reducing the laser relative intensity noise while maintaining and enhancing transmitter linearity, improving laser modulation response and increasing the laser relaxation-oscillation frequency, another application covers laser linewidth reduction to target long haul transmission and coherent detection and finally an application that requires producing a self-pulsating laser for analog to digital conversion sampling application. The performance for all these application is analyzed in both the time and frequency domains. For the analog-signal laser, a laser RIN reduction of 15 dB was realized in the simulation and experiment. For the linewidth-reduction application, the simulation also shows a reduction of linewidth from 2.4 MHz to 24 Hz can be achieved along with simultaneous reduction of 1/f noise at low frequencies, and carrier effect noise at high frequencies to flatten the laser FM response. As for the pulse-generation application, an analysis on controlling the self-pulsation characteristics of semiconductor DFB laser was performed. A detailed analysis of the noise effects on the jitter performance of this system is also carried out. This work also establishes methods to optimize and control a pulsing DFB-laser system for photonic analog-to-digital conversion application by tuning the laser drive current with the potential to replace mode-locked fiber lasers in many applications from RF photonics to chaos communication and optical signal processing.

Semiconductor lasers are essential components that enable high-speed long-haul communication and have been widely used for various applications in photonics technology. Semiconductor lasers under optical injection locking exhibit superior performance over free-running lasers and provide useful applications not achievable through the free-running lasers. The performance of injection-locked lasers has been found to be significantly improved with stronger injection. In this dissertation, the characteristics and applications of semiconductor lasers under strong optical injection locking are presented and analyzed in various aspects. First, ultra-strong (injection ratio R ̃10 dB) optical injection locking properties are investigated experimentally and theoretically. Direct modulation responses of ultra-strong optical injection-locked distributed feedback (DFB) lasers show three distinctive modulation characteristics depending on frequency detuning values. These different optical properties and electric modulation characteristics can be utilized in various applications such as analog fiber optic link, broadband digital communications, RF photonics and opto-electronic oscillators (OEOs). Using the strong injection-locked lasers, a novel single sideband generation has been demonstrated. A modulation sideband on the longer wavelength side is enhanced due to the resonant amplification by the slave laser's cavity mode, resulting in a 12-dB asymmetry at 20-GHz RF modulation. The dispersion limited RF bandwidth has been greatly increased by maintaining the variation of fiber transmission response within 7 dB up to 20-GHz RF carrier frequency over 80-km fiber transmission. Second, to improve fiber optic link performances, gain-lever distributed Bragg reflector (DBR) lasers have been fabricated. With a gain-lever modulation, 9-dB increase of a link gain has been achieved compared with a standard modulation.

Semiconductor lasers are small, reliable, low cost, high-performance and user-friendly optical devices which make them highly suitable for a variety of biomedical applications.

This dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be measured. Experimental results begin with an exploration of the consequences on the timing and amplitude jitter of the phase noise of an RF source used for mode-locking. These results lead to an ultralow timing jitter source, with 30 fs of timing jitter (1 Hz to 5 GHz, extrapolated). The focus of the work then shifts to generating a stabilized optical frequency comb. The first technique to generating the frequency comb is through optical injection. It is shown that not only can injection locking stabilize a mode-locked laser to the injection seed, but linewidth narrowing, timing jitter reduction and suppression of superfluous optical supermodes of a harmonically mode-locked laser also result. A scheme by which optical injection locking can be maintained long term is also proposed. Results on using an intracavity etalon for supermode suppression and optical frequency stabilization then follow. An etalon-based actively mode-locked laser is shown to have a timing jitter of only 20 fs (1Hz-5 GHz, extrapolated), optical linewidths below 10 kHz and optical frequency instabilities less than 400 kHz. By adding dispersion compensating fiber, the optical spectrum was broadened to 2 THz and 800 fs duration pulses were obtained. By using the etalon-based actively mode-locked laser as a basis, a completely self-contained frequency stabilized coupled optoelectronic oscillator was built and characterized. By simultaneously stabilizing the optical frequencies and the pulse repetition rate to the etalon, a 10 GHz comb source centered at 1550 nm was realized. This system maintains the high quality performance of the actively mode-locked laser while significantly reducing the size weight and power consumption of the system. This system also has the potential for outperforming the actively mode-locked laser by increasing the finesse and stability of the intracavity etalon. The final chapter of this dissertation outlines the future work on the etalon-based coupled optoelectronic oscillator, including the incorporation of a higher finesse, more stable etalon and active phase noise suppression of the RF signal. Two appendices give details on phase noise measurements that incorporate carrier suppression and the noise model for the coupled optoelectronic oscillator.

Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the "Willardson and Beer" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scientific laboratories and modern industry. - The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field

This invaluable book provides a comprehensive treatment of the design and application of Mode Locked Lasers and Short Pulse Generation. With the advances in semiconductor laser and fiber laser technologies in the 1980s to now, these devices have been made compact, refined, and developed for a wide range of applications including further scientific studies.Semiconductor mode-locked lasers are stable pulse sources and can be made over a range of wavelengths where laser operation is feasible. Rare earth doped fiber lasers or planar waveguides extend this range further and can provide compact pulsed sources. The principles of operation, analysis, design and fabrication of these sources are described. Recent results on high repetition rate and high-power pulse generation from these compacts sources are also described, together with current and future directions of application of these types of laser sources.Mode-Locked Lasers: Introduction to Ultrafast Semiconductor and Fiber Lasers is self-contained and unified in presentation. It can be used as an advanced text by graduate students and by practicing engineers. It is also suitable for non-experts who wish to have an overview of mode-locked lasers and pulse generation. The explanations in the book are detailed enough to capture the interest of the curious reader and complete enough to provide the necessary background to explore the subject further.