| Wavelength Division Multiplexing (WDM) can be an attractive alternative over Time Division Multiplexing (TDM) in fiber communications both within the inter-office links as well as in the subscriber network. As a result, components capable of multi-wavelength operation have become increasingly important. For the realization of multi-wavelength laser sources, the arrayed approach has been particularly attractive. Since the Distributed Feedback (DFB) laser is the laser diode of choice for long-haul high-speed fiber links, DFB laser arrays have received much attention in the literature recently. Nevertheless, these components have been slow to materialize due to the complexity in their design and fabrication. Hence, the theme of this thesis is to demonstrate practical and simple methods of wavelength control in Ridge Waveguide DFB laser arrays via modeling, analysis and experimental demonstration.; In the first part of this thesis, a quasi-three-dimensional model of the DFB laser is developed. In addition to the longitudinal description, a two-dimensional transverse description of the laser has been incorporated. This enables one to carry out a detailed study of the transverse ridge waveguide structure identifying its effects on the lasing performance.; In the second part of this thesis, DFB laser arrays capable of emission at multiple wavelengths are studied and experimentally demonstrated. The techniques demonstrated here are simple, inexpensive and practical. A uniform holographic exposure is used for all the lasers in the array which greatly simplifies the fabrication process. Only the final lithographic step is used for defining the wavelength. Wavelength tuning range as high as 8nm is demonstrated for the first time using ridge width and ridge tilt control. Important transverse effects such as tilt-induced transverse periodicity and their role in transverse mode selection have been identified. Other salient features such as transverse mode stability in multi-mode ridge waveguide structures and their effect on tuning range have been demonstrated. |
