Flexible Compact InGaAsP Microdisk Lasers on a Polydimethylsiloxane (PDMS) Substrate

1. Flexible Compact InGaAsP Microdisk Lasers on a Polydimethylsiloxane (PDMS) Substrate InGaAsP μ- disk 240 nm 4 × QW PDMS PMMA PMMA E-beam lithography SiNx SiNx InGaAsP InGaAsP InP InP SiNx SiNx RIE ICP InGaAsP InGaAsP μ- disk PDMS InP InP R Removed InP PDMS PDMS Kung-Shu Hsu1,2 (徐功書), Yao-Chen Wang1,3 (王耀振), Yi-Chun Yang1 (楊怡君), Shih-Kuo Tsai1,3 (蔡世國), Zi-Chang Chang1,3 (張子倉), Yu-Chen Liu1,3 (劉育辰), M. C. Wu3 (吳孟奇) and M. H. Shih1,2 (施閔雄) 1Research Center for Applied Science (RCAS), Academia Sinica, Taiwan. 2Department of Photonics, National Chiao Tung University, Taiwan. 3Department of Electrical Engineering, National Tsing Hua University , Taiwan. Address: 128 Sec.2, Academia Rd., Nankang, Taipei 11529, Taiwan Phone : 03-5712121 ext.59470, Fax : 03-5745233 Email : mhshih@gate.sinica.edu.tw Abstract : Compact microdisk cavities were fabricated on a polydimethylsiloxane substrate. The lasing of the flexible compact cavity was achieved with a low threshold power. The whispering-gallery mode of the microdisk was also characterized with finite-difference time-domain simulation. The curvature dependence in output power and threshold was also demonstrated by bending the microdisk cavity. Introduction Measurement The microdisk lasers were optically-pumped at room temperature by using an 850 nm wavelength diode laser at normal incidence with a 1.5% duty cycle and a 30 ns pulse width. • Semiconductor Microdisk Cavities • Compact size • Low threshold power • High quality factor (Q) • Polymer Photonic Devices • Application flexibility • Low cost • Special spectral properties Measurement results of a microdisk cavity with 4.75μm diameter Lasing Spectrum L-L Curve (b) (a) To demonstrate the semiconductor microdisk lasers on the flexible polymer substrate (c) (c) The lasing threshold power varied with different microdisk diameter (d) Comparison of 3D FDTD simulation and measurement spectrum (e) The top view of HZ mode profile from the 3D FDTD simulation (e) (d) Fabrication Process The structure was bended along a diameter of the disk with a small curvature (1/R) Bonded to PDMS substrate Lasing data of a bent microdisk cavity with 4.75μm diameter The SEM images of the microdisk lasers (a) The SEM image of an array of fabricated disks on the PDMS substrate with varied diameters of 1.80, 2.85, 3.80 and 4.75 μm (b) The magnified SEM image of a microdisk laser with 4.75 μm diameter Summary The compact size, flexible microdisk lasers on a PDMS substrate had been demonstrated. The lasing near 1550 nm wavelength was achieved with a low threshold power of 0.55 mW. The curvature dependence in lasing power and threshold were also characterized with the small bending of the cavities. This novel flexible microdisk laser can benefit to compact light source or sensor in the future photonic integrated systems.