Understanding of the noise characteristics of a long wavelength (LW) vertical cavity surface-emitting laser (VCSEL) under optical back reflection is crucial for its applications in optical fiber data communication. VCSELs at near 1.31μm are tested and the relative intensity noise (RIN) is measured in the presence of different levels of optical reflection intensity. Innovative LW VCSEL packaging solutions are demonstrated to achieve robust low cost error-free data
communication systems.
Since the 1990 discovery that porous silicon emits bright photoluminescence in the red part of the spectrum, light-emitting devices (LEDs) made of light-emitting porous silicon (LEPSi) have been demonstrated, which could be used for optical displays, sensors or optical interconnects. In this paper, we discuss our work on the optical properties of LEPSi and progress towards commercial devices. LEPSi photoluminesces not only in the red- orange, but also throughout the entire visible spectrum, from the blue to the deep red, and in the infrared, well past 1.5 micrometers . The intense blue and infrared emissions are possible only after treatments such as high temperature oxidation or low temperature vacuum annealing. These new bands have quite different properties form the usual red-orange band and their possible origins are discussed. Different LED structures are then presented and compared and the prospects for commercial devices are examined.
We report the results of an extensive optical characterization of the properties light-emitting porous silicon (LEPSi), using optical techniques such as Raman spectroscopy, FTIR, cw photoluminescence (PL) and time-resolved PL spectroscopy. Additional insight is obtained from several nonoptical techniques, such as optical and electron microscopy, atomic force microscopy, and various surface physics tools. We examine how to control the surface passivation of LEPSi and what the consequence for light emission are. Samples with widely different surface chemistry have been prepared by controlling the electrochemical processes during anodization or by selected post-anodization treatments such as low- and high- temperature oxidation. In particular, we discuss the relationship between the presence of Si-H, Si-O-H, and Si-O bonds, and the relative strengths of the red PL line have a microsecond(s) ec decay time and the blue PL having a Nsec decay time. These results are compared to the predictions of the leading models that have been proposed to explain the efficient room-temperature luminescence of porous silicon.
We have performed second harmonic generation (SHG) measurements in the 3 - 5 micrometers region on p-type stepped quantum wells (QWs) using the tunable, high peak power pulses generated by a free electron laser. The samples were grown by MBE on (100) GaAs wafers. The asymmetric QWs are made of m monolayers of GaAs and n monolayers of Al0.5Ga0.5As sandwiched between AlAs barriers. The QWs were characterized by x-ray diffraction and room temperature photoluminescence (PL). We measured an order of magnitude enhancement of the second order susceptibility over bulk GaAs. In contrast to n-type QWs, the dominant component is the (Chi) xyz(2) component. The results are explained by a full pseudopotential band structure calculation of (Chi) (2).
Transmission spectra recovery of CdSe, CdSxSe1-x nanocrystals and porous silicon wires optically excited by ultrashort laser pulses have been studied with picosecond time resolution using pump and probe technique. The transitions between levels of electrons and holes spatially confined within nanocrystals and thin wires were observed as bleaching bands in nonlinear transmission spectra (saturation effect). Spectra and values of third order resonant susceptibility were determined for nanocrystals of different size and porous silicon using the experimentally measured differential transmission spectra.
Strong enhancement in the second harmonic generation signal is observed in the mid-infrared in ultra-narrow p-type asymmetric GaAs quantum wells. The experiments have been performed with the high power, tunable free electron laser located at Stanford University
Transmission spectra recovery and time-resolved luminescence of CdSe microcrystals optically excited by ultrashort laser pulses have been studied with picosecond time resolution. The transitions between levels of electrons and holes spatially confined within microcrystals were observed as bleaching bands in nonlinear transmission spectra. The significant shortening of the carrier lifetime in microcrystals of smaller size was detected. The regime of laser emission at the transition between the lowest levels of size quantization was achieved.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.