Abstract
GaN-based semiconductor optical amplifier (SOA) and its integration with laser diode (LD) is an essential building block yet to be demonstrated for III-nitride photonic integrated circuits (PICs) at visible wavelength. This paper presents the InGaN/GaN quantum well (QW) based dual-section LD consisting of integrated amplifier and laser gain regions fabricated on a semipolar GaN substrate. The threshold current in the laser gain region was favorably reduced from 229mA to 135mA at SOA driving voltages, VSOA, of 0V and 6.25V, respectively. The amplification effect was measured based on a large gain of 5.7 dB at VSOA = 6.25V from the increased optical output power of 8.2 mW to 30.5 mW. Such integrated amplifier can be modulated to achieve Gbps data communication using on-off keying technique. The monolithically integrated amplifier-LD paves the way towards the III-nitride on-chip photonic system, providing a compact, low-cost, and multi-functional solution for applications such as smart lighting and visible light communications.
Highlights
The past decade witnessed the rise of III-nitride optoelectronic devices, such as violet-bluegreen light-emitting diodes (LEDs), laser diodes (LDs), modulators and photodetectors (PDs), owing to its applications in white lighting, display, optical data storage, and sensing [1,2,3,4]
This paper presents the InGaN/GaN quantum well (QW) based dual-section LD consisting of integrated amplifier and laser gain regions fabricated on a semipolar GaN substrate
The threshold current in the laser gain region was favorably reduced from 229mA to 135mA at semiconductor optical amplifier (SOA) driving voltages, VSOA, of 0V and 6.25V, respectively
Summary
The past decade witnessed the rise of III-nitride optoelectronic devices, such as violet-bluegreen light-emitting diodes (LEDs), laser diodes (LDs), modulators and photodetectors (PDs), owing to its applications in white lighting, display, optical data storage, and sensing [1,2,3,4]. Though GaAs- and InP-based PICs at the near-infrared wavelength have been studied [10], such photonic integration at the visible wavelength is still not available in III-nitride material systems Towards such integration, GaN-based core-shell nanowire LEDs and PDs were placed and patterned to demonstrate optical coupling with SiN waveguides [11]. Researchers fabricated the LED, PD and the suspended waveguide on the same GaN-onsilicon substrate [12] and such scheme enabled 30Mbps in-plane data communication link [13] Compared to those based on LEDs, the photonics integration based on LDs are promising owing to its significant higher modulation bandwidth [14, 15]. A proofof-concept Gbps data communication link by modulating the integrated amplifier was demonstrated using on-off keying (OOK) modulation scheme, suggesting the modulated SOA-LD to be a promising device for VLC applications
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