High-modulation-efficiency, integrated waveguide modulator-laser diode at 448 nm

Chao Shen, Tien Khee Ng, John T. Leonard, Arash Pourhashemi, Hassan M. Oubei, Mohd Sharizal Alias, Shuji Nakamura, Steven P. DenBaars, James S. Speck, Ahmed Y. Alyamani, Munir M. Eldesouki, Boon S. Ooi

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

To date, solid-state lighting (SSL), visible light communication (VLC) and optical clock generation functionalities in the blue-green color regime have been demonstrated based on discrete devices, including light-emitting diodes, laser diodes, and transverse-transmission modulators. This work presents the first integrated waveguide modulator-laser diode (IWM-LD) at 448 nm, offering the advantages of small-footprint, high-speed, and low power-consumption. A high modulation efficiency of 2.68 dB/V, deriving from a large extinction ratio of 9.4 dB and a low operating voltage range of 3.5 V, was measured. The electroabsorption characteristics revealed that the modulation effect, as observed from the red-shifting of the absorption edge, was resulted from the external-field-induced quantum-confined-Stark-effect (QCSE). A comparative analysis of the photocurrent versus wavelength spectra in semipolar- and polar-plane InGaN/GaN quantum wells (QWs) confirmed that the IWM-LD based on semipolar (20¯2 ¯1) QWs was able to operate in a manner similar to other III-V materials typically used in optical telecommunications, due to the reduced piezoelectric field. Utilizing the integrated modulator, a -3dB bandwidth of ~1 GHz was measured, and a data rate of 1 Gbit/s was demonstrated using on-off keying (OOK) modulation. Our experimental investigation highlighted the advantage of implementing the IWM-LD on the same semipolar QW epitaxy in enabling a high-efficiency platform for SSL-VLC dual-functionalities.
Original languageEnglish (US)
Pages (from-to)262-268
Number of pages7
JournalACS Photonics
Volume3
Issue number2
DOIs
StatePublished - Feb 5 2016

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