A Buried Silicon Nanocrystals Based High Gain Coefficient SiO 2 /SiO X /SiO 2 Strip-Loaded Waveguide Amplifier on Quartz
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1076-K05-02
A Buried Silicon Nanocrystals Based High Gain Coefficient SiO2/SiOX/SiO2 Strip-Loaded Waveguide Amplifier on Quartz Substrate Cheng-Wei Lian, and Gong-Ru Lin Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, No. 1, Roosevelt Rd. Sec. 4, Taipei, 10617, Taiwan ABSTRACT A Si-rich SiOX strip-loaded waveguide with silicon (Si) nanocrystal contributed amplified spontaneous emission at 750-850 nm with the associated spectral linewidth of 140 nm is characterized. By using the variable stripe length (VSL) method we demonstrate the optical gain and loss coefficients of 65 and 5 cm-1, respectively, for such a waveguide amplifier. The optical gain and loss coefficients are observed by fitting the one dimensional amplifier equation. The small-signal power gain of 18.4 dB at the wavelength of 805 nm under He-Cd laser pumping of 40 mW at 325 nm is obtained from the SiO2/SiOX/SiO2 waveguide amplifier with a length of 1 cm. INTRODUCTION Prior to the development of nano-synthesis technology, Si was never considered as a candidate for light emitters owing to its indirect electronic bandgap characteristics. Over the last two decades, versatile low-dimensional Si structures including nanocrystallite Si [1-2], porous Si [3], Si/insulator superlattices, and Si nano-pillars etc. with intensive luminescence and optical gain have been demonstrated [1]. The first observation on optical gain of silicon nanocrystal was proposed by Pavesi and co-workers, while the net modal gain coefficient of the silica waveguide with buried Si nanocrystal synthesized by Si+-ion implantation was determined as 100 cm-1 [1]. Later on, Luterova and co-workers also observed the optical gain and loss coefficient of 25 and 15 cm-1 [3], respectively, for the porous SiO2 nanograins embedded in SiO2 deposited by the sol-gel method. However, the gain of Si nanocrystal synthesized within the SiOX film grown by the PECVD method was seldom addressed, in which the density of Si nanocrystal is reported to be the highest among all mentioned samples. The concept and fabrication of all Si-based photonic integrated circuitry become achievable on such a mainstay semiconductor in microelectronic circuitry by employing Si based materials as alternative candidates for light emission. The aforementioned Si structure in a low-dimensional form, or the Si substrate with selected active impurities (such as erbium) inserted into Si lattice [4-5], or new composite phases (such as iron disilicide). In principle, the physical mechanism underlying the high external quantum efficiencies for photoluminescence in low-dimensional Si is mainly attributed to the quantum confinement of excitons in the nano-scale crystalline Si matrix. With the rapid evolution on the plasma enhanced chemical vapor deposition (PECVD) grown Si-rich SiOX film containing dense Si nanocrystal, the development of low-dimensional Si nanocrystal based near-infrared luminescent materials and light emitting diodes have recived much attention du
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