RESUMEN
Semiconductor colloidal nanocrystals are excellent light emitters in terms of efficiency and spectral control. They can be integrated with a metasurface to make ultrathin photoluminescent devices with a reduced amount of active material and perform complex functionalities such as beam shaping or polarization control. To design such a metasurface, a quantitative model of the emitted power is needed. Here, we report the design, fabrication, and characterization of a â¼300 nm thick light-emitting device combining a plasmonic metasurface with an ensemble of nanoplatelets. The source has been designed with a methodology based on a local form of Kirchhoff's law. The source displays record high directionality and absorptivity.
RESUMEN
Spectroscopy in the mid-infrared (mid-IR) wavelength range is a key technique to detect and identify chemical and biological substances. In this context, the development of integrated optics systems paves the way for the realization of compact and cost-effective sensing systems. Among the required devices, an integrated electro-optical modulator (EOM) is a key element for advanced sensing circuits exploiting dual comb spectroscopy. In this paper, we have experimentally demonstrated an integrated EOM operating in a wide wavelength range, i.e. from 5 to 9 µm at radio frequency (RF) as high as 1â GHz. The modulator exploits the variation of free carrier absorption in a Schottky diode embedded in a graded silicon germanium (SiGe) photonic waveguide.
RESUMEN
The integration of germanium (Ge)-rich active devices in photonic integrated circuits is challenging due to the lattice mismatch between silicon (Si) and Ge. A new Ge-rich silicon-germanium (SiGe) waveguide on graded buffer was investigated as a platform for integrated photonic circuits. At a wavelength of 1550 nm, low loss bends with radii as low as 12 µm and Multimode Interferometer beam splitter based on Ge-rich SiGe waveguide on graded buffer were designed, fabricated and characterized. A Mach Zehnder interferometer exhibiting a contrast of more than 10 dB has been demonstrated.
RESUMEN
Electro-absorption from GeSi heterostructures is receiving growing attention as a high performance optical modulator for short distance optical interconnects. Ge incorporation with Si allows strong modulation mechanism using the Franz-Keldysh effect and the quantum-confined Stark effect from bulk and quantum well structures at telecommunication wavelengths. In this review, we discuss the current state of knowledge and the on-going challenges concerning the development of high performance GeSi electro-absorption modulators. We also provide feasible future prospects concerning this research topic.
RESUMEN
Room-temperature quantum-confined Stark effect in a Ge/SiGe quantum-well structure is reported at the wavelength of 1.3 µm. The operating wavelength is tuned by the use of strain engineering. Low-energy plasma-enhanced chemical vapor deposition is used to grow 20 periods of strain-compensated quantum wells (8 nm Ge well and 12 nm Si(0.35)Ge(0.65) barrier) on Si(0.21)Ge(0.79) virtual substrate. The fraction of light absorbed per well allows for a strong modulation around 1.3 µm. The half-width at half-maximum of the excitonic peak of only 12 meV allows for a discussion on physical mechanisms limiting the performances of such devices.
RESUMEN
We report on high speed operation of a Ge/SiGe multiple quantum well (MQW) electro-absorption modulator in a waveguide configuration. 23 GHz bandwidth is experimentally demonstrated from a 3 µm wide and 90 µm long Ge/SiGe MQW waveguide. The modulator exhibits a high extinction ratio of more than 10 dB over a wide spectral range. Moreover with a swing voltage of 1 V between 3 and 4 V, an extinction ratio as high as 9 dB can be obtained with a corresponding estimated energy consumption of 108 fJ per bit. This demonstrates the potentiality of Ge/SiGe MQWs as a building block of silicon compatible photonic integrated circuits for short distance energy efficient optical interconnections.
Asunto(s)
Germanio/química , Semiconductores , Silicio/química , Resonancia por Plasmón de Superficie/instrumentación , Telecomunicaciones/instrumentación , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Teoría CuánticaRESUMEN
We report room-temperature quantum-confined Stark effect in Ge/SiGe multiple quantum wells (MQWs) with light propagating parallel to the plane of the Ge/SiGe MQWs for applications in integrated photonics. Planar waveguides embedded in a p-i-n diode are fabricated in order to investigate the absorption spectra at different reverse bias voltages from optical transmission measurements for both TE and TM polarizations. Polarization dependence of the absorption spectra of the Ge/SiGe MQWs is clearly observed. The planar waveguides exhibit a high extinction ratio and low insertion loss over a wide spectral range for TE polarization.