There is an increasing need for tuneable spectrally pure semiconductor laser sources as well as broadband and polarization insensitive semiconductor optical amplifiers based on the InGaASP/InP material system, to be monolithically integrated with other active and passive components in a photonic integrated circuit. This thesis aims to contribute to finding a solution through modelling, experimental characterization and design improvements. In this thesis we have analyzed laterally-coupled distributed feedback (LC-DFB) lasers. These lasers have the gratings etched directly out of the ridge sidewalls thus lowering the cost associated with the re-growth process required if the gratings were otherwise embedded above the active region. The performance characteristics are analyzed for the LC-DFB lasers partitioned into 1-, 2-, and 3-, electrodes with individual bias control at various operating temperatures. The laser exhibits a stable single mode emission at 1560 nm with a current tuning rate of ~14 pm/mA for a tuning of 2.25 nm. The side modes are highly suppressed with a maximum side-mode suppression ratio of 58 dB. The light-current characteristics show a minimum 40 mA threshold current, and power saturation occurring at higher injection currents. The linewidth characteristics show a minimum Lorentzian linewidth of 210 kHz under free-running and further linewidth reduction under feedback operation. The multi-electrode LC-DFB laser devices under appropriate and selective driving conditions exhibit a flat frequency modulation response from 0 to above 300 MHz. The multi-electrode configuration can thus be further exploited for certain requirements. Simulation results and design improvements are also presented. The experimental characterization of semiconductor optical amplifier (SOA) and Fabry-Perot (FP) laser operating in the E-band are also presented. For the SOA, the linear vertical and horizontal states of polarization corresponding to the transverse electric (TE) and transverse magnetic (TM) modes were considered. For various input power and bias, performance characteristics shows a peak gain of 21 dBm at 1360 nm, gain bandwidth of 60 nm and polarization sensitivity of under 3 dB obtained for the entire wavelength range analyzed from 1340 to 1440 nm. The analysis presented in this thesis show good results with room for improvement in future designs.

The FP multimode semiconductor laser has lightened up a new field of optical communication technology in the past two decades. Numerical modeling of its physical behaviours and transient response has been discussed previously in literature, mostly by constructing the multimode rate equations. Rate equations are very helpful in studying and predicting the average photon and carrier transient response and relaxation oscillation. However, their deficiency in statistical photon fluctuation limits the function of describing stochastic power shifted from main mode to other side modes. Therefore, a noise driven model with conjunction of optical fibre and photodiode is built to form an optical communication system in the simulation scope. The multimode nature of FP lasers causes several problems such as mode partitioning noise (MPN), intersymbol interference (ISI), and frequency chirping, among which mode partitioning noise is the most serious of the concern in this discussion. The stereotype analytical measurement of MPN power penalty is based on several assumptions on the received waveform shape and power distribution spectrum, which limits its fields of application and accuracy. This work develops a numerical solution to power penalty due to MPN, and it can be employed to any multimode laser diode models regardless of the received signal shape and power distribution spectrum. In conclusion, the MPN power penalty is a significant profile of evaluating system perform in fibre-optic communication links. It highly depends on shape of power distribution spectrum, number of modes, length of fibre, and pattern of signal waveform. / Thesis / Master of Applied Science (MASc)

The bandwidth demanding in the access network has been increasing rapidly over the past several years. The predominant broadband access network solutions deployed today are digital subscriber line (DSL) and community antenna television (CATV) (cable TV) based networks. However, the passive optical network (PON) which is a point to multipoint access network based on optical fibers provides much higher bandwidth compared to current access networks based on copper lines. Incorporating wavelength division multiplexing (WDM) in a PON allows a much higher bandwidth compared to the standard PON which operates in the single wavelength mode where the one wavelength is used for upstream transmission and another different wavelength is used for downstream transmission. Moreover, WDM-PON offers the advantages in terms of capacity, low latency and service transparency. In the past five years WDM-PON technology has been developed to a mature for commercial consideration. In this thesis, we start from some fundamentals about WDM-PON and the technology challenge for WDM-PON which is to avoid the need for expensive wavelength selective optical components in the end-user optical network unit (ONU). Then we investigate Injection Locked Fabry-Perot Laser Diode with narrow band amplified spontaneous emission (ASE) noise as an approach to be a wavelength independent ONU. We study its theoretical model and compare the experimental results with the simulation results based on the theoretical model. / Thesis / Candidate in Philosophy