Physics Chat cancelled
Novel VCSEL Geometries for Miniaturised Magnetometers
Speaker: James Meiklejohn (Dr Samuel Shutts's group)
Date: Thursday 16 March 2023
Time: 14:30
Venue: Translational Research Hub Seminar Room 0.02
We investigate the suitability of different device designs for Vertical Cavity Surface Emitting Lasers (VCSELs) intended for use in miniaturised magnetometers required in applications such as geophysical mapping, underwater ordinance detection and monitoring electrical pulses generated within the human body. Novel geometries are motivated by the requirement to increase the output power while maintaining beam quality and optical coherence, and we explore the use of multiple closely-spaced emitters that can be coupled together in-plane to create a single output.
Variations in the design and spacing of the devices geometry are examined, and the results discussed with reference to the physical mechanisms involved in the coupling, including the in-plane propagation of the optical field and the effect of the mesa shape on reflections in the lateral direction. The threshold current, maximum output power and side-mode suppression ratio are measured at a range of temperatures up to the operating temperature of 75 deg.C, and we compare the key operating characteristics of conventional and novel device designs. With reference to the requirements of the application, such as single-mode emission at the caesium D2 transition at 852.2 nm and with output-powers over 1 mW, we identify the best-performing devices and briefly discuss the suitability of these devices as optical sources in miniature magnetometers.