Whispering-gallery modes and light emission from a Si-nanocrystal-based single microdisk resonator

Abstract

We report on visible light emission from Si-nanocrystal based optically active microdisk resonators. The room temperature photoluminescence (PL) from single microdisks shows the characteristic modal structure of whispering-gallery modes. The emission is both TE and TM-polarized in 300 nm thick microdisks, while thinner ones (135 nm) support only TE-like modes. Thinner disks have the advantage to filter out higher order radial mode families, allowing for measuring only the most intense first order modal structure. We reveal subnanometer linewidths and corresponding quality factors as high as 2800, limited by the spectral resolution of the experimental setup. Moreover, we observe a modification of mode linewidth by a factor 13 as a function of pump power. The origin of this effect is attributed to an excited carrier absorption loss mechanism.

Thermo-optic coefficient of silicon at 1550 nm and cryogenic temperatures

“…7 Besides the mentioned macroscopic metrological applications silicon is also a candidate material for microscopic applications such as whispering gallery resonators. 8,9 With their sharp optical spectra these devices promise advantages in the fields of spectroscopy and sensing. Thermo-refractive noise was also identified to strongly limit the scope of these microscopic resonators.…”

“…It provides a tunable wavelength between 1440 nm and 1640 nm and a maximum output power of about 20 mW. Using a non-polarizing beam splitter (8) a fraction of the incident light was directed onto a photo diode (9). Its signal was used for normalization of the reflected and transmitted power.…”

Whispering gallery modes at 800 nm and 1550 nm in concentric Si-nc/Er:SiO2 microdisks

“…Based on the free spectral range (FSR) observed for concentric disks with varying Er:SiO 2 widths, we confirm that the Si-nc based WGMs are confined at the outer edge of the Er:SiO 2 ring. Despite the interfaces involved, the quality factors for these WGMs are similar to those for typical Si-nc microdisks [8,9].…”

“…Efficient photoluminescence (PL), electroluminescence (EL), and optical gain have been demonstrated in Si-nc films [5,6]. Recently, Si-nc microdisks have been fabricated demonstrating enhanced spontaneous emission and WGMs with quality factors on the order of 10 3 [7][8][9]. A major factor limiting the use of Si-nc as a lasing material is the presence of free carrier absorption under high pump powers.…”

Towards low energy consumption integrated photonic circuits based on Ge/SiGe quantum wells

“…Different possibilities are investigated to get a light source in silicon such as the use of erbium doped silicon [5] or silicon-nanocrystal [6]. Electrically-pumped laser source on silicon has been successfully demonstrated, either by using strained and doped germanium (Ge) [7], or by integrating III-V on silicon (Si) [8,9].…”