Title :
Optimization of Si1-xGex/Si waveguide photodetectors operating at λ=1.3 μm
Author :
Naval, L. ; Jalali, B. ; Gomelsky, L. ; Liu, J.M.
Author_Institution :
ETSI Telecomunicacion, Univ. Politecnica de Madrid, Spain
fDate :
5/1/1996 12:00:00 AM
Abstract :
This paper analyzes the influence of various design parameters in the external quantum efficiency (QE) of waveguide detectors based on Si/Si1-xGex strained-layer superlattices (SLSs), for use in optical communications at λ=1.3 μm. The study presents an algorithm that automatically generates structurally stable SLSs. This generation is completed by intensive simulation of the generated SLSs to calculate the external QE. The simulation embraces optical waveguiding, absorption, quantum size effect, as well as thermodynamics of the strained layers. Two sets of data were created using two different models for the SiGe layer critical thickness, hc(x). A conservative model for hc, corresponding to the equilibrium regime, yielded discrete maximum values for QE (around 12%) that were mainly dependent on the alloy absorption. A second model for hc, corresponding to the metastable regime, produced considerably higher QEs (around 60%), and shows the great importance of fiber-to-waveguide coupling efficiency. The importance of the passive-waveguide coupler geometry is investigated using the beam propagation method
Keywords :
Ge-Si alloys; infrared detectors; optical design techniques; optical fibre couplers; optical waveguide theory; optical waveguides; optimisation; photodetectors; semiconductor device models; semiconductor superlattices; thermodynamics; 1.3 mum; 12 percent; 60 percent; Si/Si1-xGex strained-layer superlattices; Si1-xGex/Si waveguide photodetectors; SiGe layer critical thickness; SiGe-Si; alloy absorption; beam propagation method; design parameters; external QE; external quantum efficiency; fiber-to-waveguide coupling efficiency; intensive simulation; metastable regime; optical absorption; optical communications; optical waveguiding; passive-waveguide coupler geometry; quantum size effect; simulation; strained layers; structurally stable SLSs; thermodynamics; waveguide detectors; Absorption; Germanium silicon alloys; Metastasis; Optical design; Optical fiber communication; Optical fiber couplers; Optical superlattices; Optical waveguides; Silicon germanium; Thermodynamics;
Journal_Title :
Lightwave Technology, Journal of
