Author Affiliations
1State Key Laboratory on Tunable Laser Technology, School of Electronic and Information Engineering, Harbin Institute of Technology, Shenzhen 518055, China2LTCI, Telecom Paris, Institut Polytechnique de Paris, 91120 Palaiseau, France3DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, 2800 Lyngby, Denmark4School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China5Center for High Technology Materials, The University of New-Mexico, Albuquerque, New Mexico 87106, USAshow less
Fig. 1. Optical spectrum of (a1) sole GS lasing and (a2) dual-state lasing of QD lasers. (b) Optical spectrum mapping with the increase of bias current for the dual-state QD laser. Dashed lines (1) and (2) in (b) mark the bias currents of (a1) and (a2), respectively.
Fig. 2. Experimental setup for investigating the feedback sensitivity of QD lasers. BKR, backreflector; PC, polarization controller; OSA, optical spectrum analyzer; PD, photodiode; ESA, electrical spectrum analyzer.
Fig. 3. Optical (column 1) and RF (column 2) spectrum mappings for QD laser operating at (a) 0.72×, (b) 1×, and (c) 1.25×IthES. Dashed lines mark the critical feedback levels.
Fig. 4. (a) Optical and (b) RF spectra of QD lasers operated at 1×IthES subject to high feedback strength of −9.9 dB (red) and low feedback strength of −29 dB (blue).
Fig. 5. Schematic representation of the electronic structure and carrier dynamics of QD lasers under optical feedback.
Fig. 6. GS threshold current, ES threshold current, and corresponding ES-GS threshold ratio with respect to ES-GS energy separation.
Fig. 7. Samples of the bifurcation diagrams (column 1), time series (column 2), and GS phase portraits (column 3). (a) ΔEGSES=65 meV, I/IthES=1.0, and fext=−12.0 dB; (b) ΔEGSES=80 meV, I/IthES=1.31, and fext=−11.0 dB; (c) ΔEGSES=110 meV, I/IthES=0.87, and fext=−13.0 dB. Green vertical dashed lines in the first column mark the fext taken in the second and third columns; rcrit extracted from the bifurcation diagrams are marked in the first column.
Fig. 8. Critical feedback levels as a function of normalized bias currents (I/IthES). Triangles, diamonds, and squares are numerically calculated for different ES-GS energy separations, while the dots are extracted from measurement results.
Fig. 9. Linewidth enhancement factor as a function of normalized bias currents (I/IthES) for GS and ES, respectively.
Fig. 10. Damping factor and relaxation oscillation frequency versus normalized bias currents (I/IthES).
Symbol | Description | Value |
---|
| RS transition energy | 0.97 eV | | ES transition energy | 0.87 eV | | GS transition energy | 0.82 eV | | RS to ES capture time | 6.3 ps | | ES to GS relaxation time | 2.9 ps | | ES to RS escape time | 2.7 ns | | GS to ES escape time | 10.4 ps | | RS spontaneous emission time | 0.5 ns | | ES spontaneous emission time | 0.5 ns | | GS spontaneous emission time | 1.2 ns | | Group velocity | | | Spontaneous emission factor | | | Optical confinement factor | 0.06 | | Photon lifetime | 4.1 ps | | Internal round trip time | 11.7 ps | | External round trip time | 2.0 ns | | Facet reflectivity | 0.32 | | GS differential gain | | | ES differential gain | | | RS differential gain | | | ES gain compression factor | | | GS gain compression factor | | | Total dot number | | | Total RS state number | | | Active region volume | | | RS region volume | | | Polarization dephasing time | 0.1 ps |
|
Table 1. Parameters Used in the Simulation