Lasing Properties of Microcavity Semiconductor Lasers and Spatial Coherence in Gain Profiled Semicnductor Lasers with Optical Feedback - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Lasing Properties of Microcavity Semiconductor Lasers and Spatial Coherence in Gain Profiled Semicnductor Lasers with Optical Feedback write by Guan Hong Wu. This book was released on 2004. Lasing Properties of Microcavity Semiconductor Lasers and Spatial Coherence in Gain Profiled Semicnductor Lasers with Optical Feedback available in PDF, EPUB and Kindle. Investigated in this thesis are some methods to control the optical modes of semiconductor lasers with different cavity geometries such as microdisks, microrings, and broad-area lasers with external cavities. The characteristics of lasing spectra from microdisk and microring semiconductor lasers are examined in detail. Microcavity devices are mounted on either glass substrate or the end facet of a multi-mode optical fiber, which is first realised in the mounting technology area of microcavity lasers. Under optical pumping in pulsed or continuous wave condition at room temperature, all sample devices achieved lasing. Lasing modes have been identified to be consistent with Whispering-Gallery modes. Quality factors are estimated to be of the order of 2500. We also observed for the first time that the mode spectral broadening with microring devices under high pulsed pump powers is attributed to the transient red shift of the lasting mode. These work show that optical pumping is an easy and flexible way to study lasing characteristics of semiconductor microcavity lasers. We can control the wavelength and intensity of optical modes in these devices through changing their diameters and varying their geometries. Two mounting configurations expand the optical pumping schemes and application areas with microcavity lasers. Mounting microcavities on the end facet of fiber will find possible applications in the integrated optical circuit, in which microcavity devices can be coupled with optical fiber as filters, add-drop filters, etc. Further work needs to be done on mounting microcavity devices at the end facet of a single-mode fiber due to the wide adoption of this fiber in telecommunication systems. How the optical feedback from an external cavity affects the spatial coherence of optical modes in gain profiled broad area semiconductor lasers consists of another part of the research work in this thesis. This device shows good spatial coherence with increasing output optical field under pulsed operation but has limited operation range with good spatial coherence under CW condition. The optical feedback reduces the threshold current of the gain profiled device by up to 8%. This is a trivial improvement that could lead to higher reflective coatings on the facets of laser diode. Feedback also restores the symmetry of beam profiles and increases the total intensity of the output beam without degrading its spatial coherence. It reduces the effect of any local perturbations in the thermal lens profile. The appearance of interference fringes between the near field profile segments when the feedback mode matches the output mode perfectly is another evidence of the food spatial coherence with this device. Simulations based on the modified Maxwell-Bloch equation verify the above experimental results.
Microcavity Semiconductor Lasers
Microcavity Semiconductor Lasers - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Microcavity Semiconductor Lasers write by Yong-zhen Huang. This book was released on 2020-08-17. Microcavity Semiconductor Lasers available in PDF, EPUB and Kindle. The book focuses on unidirectional-emission microcavity lasers for photonic integrated circuits, including polygonal microresonators, microdisk and microring lasers. It first gives an introductory overview of optical microcavities for microlasers, followed by the detailed information of the integrable microcavity semiconductor lasers, such as the mode structure control and characteristics, the lasing properties, microcavity fabrication and applications of different microcavity lasers.
Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards
Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards write by . This book was released on 2006. Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards available in PDF, EPUB and Kindle.
Spatial beam-output characteristics of semiconductor lasers with optical feedback
Spatial beam-output characteristics of semiconductor lasers with optical feedback - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Spatial beam-output characteristics of semiconductor lasers with optical feedback write by Vahid Gregory Taʼeed. This book was released on 1998. Spatial beam-output characteristics of semiconductor lasers with optical feedback available in PDF, EPUB and Kindle.
Modal Properties of Semiconductor Lasers
Modal Properties of Semiconductor Lasers - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Modal Properties of Semiconductor Lasers write by Yann Tanguy. This book was released on 2005. Modal Properties of Semiconductor Lasers available in PDF, EPUB and Kindle. The importance of semiconductor lasers has grown steadily over the years, these devices being now essential in a wide range of fields. This includes optical reading and writing of stored data, light source for optical fibres in telecommunications, medical applications, laser printing {u2026} There is an ever expanding need for higher output power and higher brightness from semiconductor devices. This can be achieved with various approaches. Unstable resonators use cavity designs with curved mirrors to yield a highly divergent beam, and counteract the self-focusing tendency of the light in laser materials. These resonators also increase the transverse mode discrimination. Both characteristics improve the beam quality, and make these devices attractive for fibre coupling applications, such as transfer of data for telecommunications. Different cavity geometries with an internal beam waist were tested, and did not display the same behaviour. In some cases we observed a displacement of the beam waist due to thermal lensing, which is not desired for fibre coupling schemes. With modelling and experimental investigations we explained this phenomenon, and proposed some cavity designs to alleviate this problem. The effect of optical feedback in lasers is a common cause of beam deterioration. Feedback on self-pulsing devices is still an important area to explore and comprehend, as this affects applications (such as optical data storage) requiring self-pulsing output powers. Some of the unstable resonators displayed self-pulsing dynamics, and the indluence of optical feedback was analysed, first experimentally, andd then theoretically with a model based on Lang-Kobayashi equations. The appearance of perturbations in the optical intensity is suggested to be linked with transition between limit cycles. The properties of semiconductor materials can also improve the beam quality. Intense research is currently focusing on Quantum Dot (QD) materials, containing nanostructures as small as 10nm which provide a nearly quantised optical gain for lasing action. Many improvements and specific characteristics are expected from these QD devices, particularly an improvement of the spatio-temporal stability of the beam. The transverse modes of broad are QD devices were experimentally examined, and dynamic instabilities characterised. The temperature profile was found to be beneficial to the transverse mode stability. In narrow wave-guide devices, simultaneous lasing in both the low and high energy levels was investigated. Simulations explained the observed decay of the low energy level lasing with increasing current. And strong antiphase dynamics were recorded between the high and low level output powers, at relatively low frequencies (below 50 M H z). Finally, interactions between longitudinal Fabry-Perot modes displayed some interesting and complex features. The output power dynamics were found to be chaotic, and the modal coupling via homogeneous broadening resulted in the appearance of frequency synchronisation. And cross-correlation measurements between modes exhibited a modal switching sequence from blue to red wavelengths, which appear to differ from periodic antiphase dynamics reported for quantum well lasers.
