Title

Investigation of grating coupled surface emitting lasers

Date of Completion

January 2001

Keywords

Engineering, Electronics and Electrical|Physics, Optics

Degree

Ph.D.

Abstract

Three unique laser properties that are difficult to obtain from other known diode laser structures were demonstrated using a laser structure called GCSEL (Grating Coupled Surface Emitting Laser). These properties are (1) high power; (2) wide continuous frequency tuning; (3) tunable pico-second pulse generation. ^ High power GCSEL devices were studied. Grating performance under different configuration was evaluated. Up to 1W peak power were obtained from 2 nd order GCSEL. A simplified model was used to explain the results and analysis lead to a detuned 2nd order GCSEL device. We have demonstrated up to 8 Watts output power from such a single device. ^ Record high broad continuous tuneability (132nm centered at 980nm or about 14% tuning of the gain-line center) using a simple, compact external cavity GCSEL was demonstrated. Such EC-GCSEL has advantage of non-requirement of AR coating and near diffraction-limited beam. Tuning properties of the EC-GCSEL were studied. Different approaches to achieve broader tuning were studied. Applying same concept to longer wavelength region will be able to achieve broader tuning. ^ Tuneable, pico-second pulse generation from a compact external cavity GCSEL was demonstrated. 150 pico-second pulses with 60nm tuneability centered at 980nm were obtained from external cavity GCSEL devices by gain switching. Using 2nd order GCSEL, 60 pico-second pulses with several hundreds mili-watts was obtained. It is clearly showed that the minimum pulse width from a gain switched GCSEL has a linear relation with the effective cavity length, thus one can achieve shorter pulses using a shorter external cavity GCSEL. Our approach can work at any arbitrary frequency, it is one of the simplest design aimed at low cost device for various applications in time domain spectroscopy. ^