Abstract
We report on the design, fabrication and optical performance of gain mirrors in single crystal diamond substrates for vertical external cavity surface emitting lasers (VECSELs). VECSELs have gained attention recently due to their potential for high emission power in single mode with low beam divergence, yet their maximum output power remains typically limited due to thermal roll-over resulting from insufficient heat dissipation. In order to increase the heat transfer, we exploit the excellent thermal conductivity of single crystal diamond, which is assembled in direct contact with the active structure. The optical cavity is hereby defined by an output coupler and a high reflection grating structure etched into the diamond surface. We here present the design and microfabrication of a diffraction grating that was optimized to reflect light into the 0th order, therefore combining the role of a gain mirror and a heatsink at the same time. Our process involved metal mask deposition onto the diamond surface, e-beam lithography and reactive ion etching. Characterization showed reflection above 95% at a center wavelength of 1550 nm, potentially allowing the integration of the diamond mirror into a vertical external cavity surface emitting laser.
Highlights
Vertical external cavity surface emitting lasers (VECSELs) are semiconductor light sources that provide high optical output power simultaneously with excellent optical beam quality [1]
Due to limited heat dissipation, VECSELs with emission wavelength above 1200 nm are typically limited in efficiency, with achievable output power typically limited to a few mW [2]
While diffraction gratings in diamond have been demonstrated previously [19,20,21], we here demonstrate a high contrast gratings (HCG) design that was configured to achieve higher than 95% reflectance at operating wavelength of 1550 nm into the 0th order, which is an essential requirement for integration in VECSEL structures
Summary
Vertical external cavity surface emitting lasers (VECSELs) are semiconductor light sources that provide high optical output power simultaneously with excellent optical beam quality [1]. In order to improve their performance, several approaches have been demonstrated previously, including integration of heat spreaders to the gain mirrors [3], employing diamond [4] or silicon carbide [5], or decreasing the thermal resistance of the substrate and distributed Bragg reflector (DBR) by electroplated gold [6,7]. Despite these improvements emission power currently remains limited to 106 W at 1028 nm wavelength [8], 33 W at 1275 nm [9], and 1 W at 1560 nm [10]. While diffraction gratings in diamond have been demonstrated previously [19,20,21], we here demonstrate a HCG design that was configured to achieve higher than 95% reflectance at operating wavelength of 1550 nm into the 0th order, which is an essential requirement for integration in VECSEL structures
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
