Abstract
We report on the characterization and analysis of a GaN-based distributed feedback laser diode (DFB-LD) with 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> -order laterally etched sidewall gratings centered at a wavelength of 420 nm. We also compare the device parameters with two commonly used Fabry-Perot (FP) devices operating at 450 nm and 520 nm. Intrinsic properties of the devices were extracted, including damping factor, carrier and photon lifetimes, modulation efficiency, differential gain, and parasitic capacitance. These parameters showed that the DFB exhibits a lower damping rate and parasitic capacitance while demonstrating a higher modulation efficiency, indicating that the DFB shows good potential for communications applications. Additionally, spectral linewidth of a GaN DFB is reported. To the authors' knowledge, this is the first demonstration of parameter extraction and spectral linewidth measurement for GaN-based DFB-LDs.
Highlights
Gallium Nitride (GaN)-based devices have been the focal point of significant research interest over the past three decades, since Nakamura demonstrated their value as LEDs [1]
GaN-based laser diodes (LDs) are a potentially key component in visible light communication (VLC) systems, with higher modulation bandwidth and output power capabilities compared to their LED counterparts
This work will better characterize the carrier transport effects found in GaN-based distributed feedback (DFB), and indicate where improvements need to occur such that visible light devices can compete with the modulation characteristics of more established telecommunications LD technologies
Summary
Gallium Nitride (GaN)-based devices have been the focal point of significant research interest over the past three decades, since Nakamura demonstrated their value as LEDs [1]. The results found for the DFB device will be compared to calculated values for commercial blue and green GaN FP devices, to demonstrate the feasibility of GaN-based laterally-coupled (LC) DFBs for the applications previously mentioned These devices have been well-investigated by several research groups [2], [27], [29]–[33], and provide a benchmark for GaN-based device performance. Following investigation into parameter extraction methods for GaN DFBs, spectral linewidth measurements will be discussed This is a important parameter for quantum cooling applications, as well as in communications applications, where a narrow linewidth can allow for precise wavelength division multiplexed (WDM) systems. This setup would require several devices, with central wavelengths separated by as little as 1 nm, operating in a multiplexed system for high data rate VLC systems, similar to that described in [31], which is a potential application with suitable optical filtering [34]
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