Theoretical analysis for effect of facet reflections on amplification and noise characteristics in semiconductor optical amplifier

In most cases, the semiconductor optical amplifiers (SOA) are used with anti-reflection coating for its facets to avoid laser oscillation. Providing effects by residual reflection at the facets are theoretically analyzed. When the reflection by the back facet exists, the SOA shows larger amount of the amplified spontaneous emission as well as the larger intensity noise. When the reflection by the front facet exists, amplification ratio is reduced. However, the spectral linewidth of the inputted optical signal is never changed by amplification in the SOA, even the facets have residual reflectivities

Computer Simulation of Feedback Induced Noise in Semiconductor Lasers Operating with Self-Sustained Pulsation

大学院自然科学研究科電子科

Theoretical Proposal for a Unidirectional Optical Amplifier

The possibility of achieving a unidirectional optical amplifier is theoretically predicted with a model in the vacuum environment. The operation of this amplifier is based on the transfer of the kinetic energy of an electron beam to an optical one where both are propagating in the same direction. The optical beam propagates in a dielectric waveguide where it partly penetrates into the vacuum in the form of an evanescent wave. The electron beam is emitted from an electron gun and propagates along the surface of the dielectric waveguide, exciting the optical beam. The propagation speed of the optical beam is slowed down with the aid of the dielectric waveguide and is made to coincide with that of the electron beam. Quantum mechanical analysis of the interaction between the optical beam and the electron beam is given, based on the density matrix formalism. At the wavelength of 0.5 μm, the gain coefficient is calculated to be about 12 cm-1 under the excitation voltage of 64 kV and the electron beam current of several microampere

Analysis of intensity and frequency noises in semiconductor optical amplifier

A theoretical analysis of the intensity and the frequency noise in semiconductor optical amplifiers (SOA) is given. Amplification of a traveling optical wave is formulated associating with fluctuations on the optical intensity, the optical phase, and the electron numbers based on the classical wave-equation and quantum mechanical modification. Inclusion of the amplified spontaneous emission generated in the SOA is also taken into account. Amounts of noise are expressed in terms of the relative intensity noise (RIN), the spectrum line-width, and the frequency noise. Sensitive dependency of the RIN property on the optical input power is theoretically explained. The RIN increases after passing the SOA, when the optical input power is small enough, but decreases when the optical input power is rather high. On the while, the spectrum line-width is found to be scarcely changed from the input light for conventional operation of the SOA. © 2012 IEEE

A Theoretical Analysis of Quantum Noise in Semiconductor Lasers Operating with Self-Sustained Pulsation

大学院自然科学研究科電子科