1 Single-mode 1.52 μm InAs/InP quantum dot DFB lasers Z.G. Lu 1 , P. Poole 1 , P. Barrios 1 , Z.J. Jiao 1,2 , J.R. Liu 1 , G. Pakulski 1 , D. Goodchild 1 , B. Rioux 1 , A.J. Springthorpe 1 , and D. Poitras 1 1 Ins. for Microstructural Sciences, National Research Council, Ottawa, ON, Canada 2 Dept. of Electrical & Computer Eng., Concordia University, Montreal, QC, Canada Zhenguo.Lu@NRC-CNRC.GC.CA Abstract: Single-mode InAs/InP quantum dot DFB lasers with side-mode suppression ratio greater than 62 dB are demonstrated, operating CW up to 80°C. Relative intensity noise was less than -153 dB/Hz from 1 MHz to 10 GHz. ©2011 Optical Society of America. OCIS codes: (250.5590) Quantum-well, -wire and –dot devices; (140.3490) Lasers, distributed-feedback; 1. Introduction Advances in the growth of self assembled quantum dots (QDs) for applications in optical devices such as laser diodes and optical amplifiers have attracted considerable attention due to the potential advantages of QDs as a gain material [1]. More specifically, QD lasers as compared with conventional bulk and quantum well (QW) semiconductor lasers have exhibited lower threshold, better temperature stability, decreased sensitivity to back- reflections, shorter recovery times, reduced chirp and smaller linewidth enhancement factor. Utilizing some of these QD properties we have successfully demonstrated QD multi-wavelength lasers (QD-MWLs) [2, 3], and femtosecond (fs) pulse generation from passive C- and L-band mode-locked lasers (QD-MLLs) [4, 5]. In this paper, we demonstrate continuous-wave (c.w.) InAs/InP QD distributed feedback (DFB) lasers operating at 1.5 µm with a cavity length of 1 mm and ridge width of 3 μm. One of the cleaved facets was coated with a high reflectivity coating of 65%, the other had a 2% anti-reflectivity coating. Output power at a temperature of 20 °C is 9 mW with a threshold current density of 1250 A/cm 2 . At a DC driving current of 150 mA the side mode suppression ratio (SMSR) and the optical linewidth of the QD DFB laser were greater than 62 dB and less than 250 KHz respectively. The relative intensity noise (RIN) was below -153 dB/Hz in the frequency range from 1 MHz to 10 GHz. Using the injection locking technique, the linewidth enhancement factor (LEF) above threshold was measured to be below 2. (a) (b) Figure 1. (a) Cross-sectional SEM image of the completed laser structure showing the QD core and the floating grating, and (b) plan view SEM of the etched grating before top layer overgrowth. 2. Design, growth, fabrication and processing of InAs/InP QD DFB lasers The InAs/InP QD DFB gain material used in this study was grown by chemical beam epitaxy (CBE) on a (100) oriented n-type InP substrate. The undoped active region of the laser consisted of five stacked layers of InAs QDs with 30 nm In 0.816 Ga 0.184 As 0.392 P 0.608 (1.15Q) barriers. The QDs were tuned to operate in the desirable operation wavelength range by using a QD double cap growth procedure and a GaP sublayer [6]. Growing the dots on a thin GaP layer allows a high dot density to be obtained and improved layer uniformity when stacking multiple layers of dots, providing maximum gain. This active layer was embedded in a 350 nm thick 1.15Q waveguiding core, OWD6.pdf OSA/OFC/NFOEC 2011 OWD6.pdf