Electrical and Computer Engineering ETDs


Aaron Moscho

Publication Date



The study of injection locking characteristics was performed on an InAs Quantum Dash (QDash) semiconductor laser for the first time. The linewidth enhancement factor(α-parameter) of a QDash laser was measured using an injection locking technique that takes advantage of the asymmetry of the injection range. Studies were performed as functions of injecesed photon density, wavelength, and output power. To understand the behavior of the α-parameter versus wavelength, the Hakki-Paoli method, a technique that utilized the below threshold amplified spontaneous emission spectrum, was used to measure the modal gain over 1550 nm to 1573 nm. The α-parameter was found to have changed dramatically with power, indicating a large nonlinear gain coefficient, ε. Using a curve fit of the α versus power curve taken from the injection locking data, ε was measured to be 1.4*10-14 cm3, 1000 times larger than the typical ε of quantum well lasers, changing the dynamics of the laser. The small α-parameter and giant ε dramatically change the dynamics of the laser. To study the effects of the small α-parameter and giant ε further, an operational map was created using an Agilent Technologies High Resolution Spectrometer (HRS) with a resolution of 1 MHz. The new operational map of the InAs QDash laser has features never before seen with other devices, such as the avoidance of coherence collapse with optical feedback.


Injection lasers, Indium arsenide, Quantum dots.

Document Type




Degree Name

Electrical Engineering

Level of Degree


Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Ghani, Nasir

Second Committee Member

Sheik-Bahae, Mansoor