Silicon-on-insulator (SOI) has been used as a platform for nearinfrared photonic devices for more than twenty years. Longer wavelengths, however, may be problematic for SOI due to higher absorption loss in silicon dioxide. In this paper we report propagation loss measurements for the longest wavelength used so far on SOI platform. We show that propagation losses of 0.6-0.7 dB/cm can be achieved at a wavelength of 3.39 µm. We also report propagation loss measurements for silicon on porous silicon (SiPSi) waveguides at the same wavelength.

We report modulation of the absorption coefficient at 1:3 μm in Ge/SiGe multiple quantum well heterostructures on silicon via the quantum-confined Stark effect. Strain engineering was exploited to increase the direct optical bandgap in the Ge quantum wells. We grew 9 nm-thick Ge quantum wells on a relaxed Si 0:22 Ge 0:78 buffer and a contrast in the absorption coefficient of a factor of greater than 3.2 was achieved in the spectral range 1290-1315 nm. © 2011 Optical Society of America OCIS codes: 230.4110, 230.4205, 250.4110, 250.5590, 260.6580. Existing silicon Mach-Zehnder modulators that exploit the carrier dispersion effect are typically either large and dissipate considerable amounts of power [1] or require the use of resonant cavities, which have temperature stabilization issues and are very sensitive to fabrication tolerances. The development of silicon-based electroabsorption modulators (EAMs) is desirable for emerging silicon photonics applications, including optical network interconnects and fibre-to-the-home, because such devices can have a small footprint, low power consumption, and good temperature stability. Several optical fiber telecommunications systems exploit the spectral 'window' around 1:3 μm, which corresponds to zero dispersion in standard single-mode fibers. In particular, some passive optical network (PON) architectures use 1:3 μm radiation for upstream signals [2]. Therefore, it is desirable to fabricate optical modulators that can operate at this wavelength. Ge/SiGe multiple quantum well (MQW) heterostructures can be epitaxially grown on silicon wafers using a relaxed buffer layer (see, e.g., [3]), where the alternating layers should be strain-balanced to the buffer layer so that no net strain accumulates in the MQW stack. Previous studies of the quantum-confined Stark effect (QCSE) in Ge/SiGe MQW structures have reported buffers layers with a Ge fraction of 90% or more [4][5][6][7]. Here, we describe absorption spectra for a strain-balanced stack of ten 9 nm thick Ge quantum wells and eleven 7 nm thick Si 0:4 Ge 0:6 barriers grown on a relaxed Si 0:22 Ge 0:78 buffer. The large compressive strain in the Ge quantum wells results in an increase in the direct bandgap compared with relaxed Ge, which results in a blue-shift of the absorption edge, and proper choice of the layer widths and compositions allows us to control the absorption edge of the structure [8].The MQW heterostructures were grown using reduced pressure chemical vapor deposition (RP-CVD) on a relaxed Si 0:22 Ge 0:78 buffer. The buffer was grown using reverse linear grading (RLG) from a relaxed Ge seed layer, which was grown on an Si substrate [9]. Further details of the epitaxial growth can be found in [10]. Circular mesa devices of 80 μm diameter were defined using optical lithography and reactive-ion etching and a Ti/Al metal stack was deposited and sintered at 400°C for 30 minutes to form electrical contacts. A schematic diagram of the cross section of the devices is shown in Fig. 1.Absorption spectra were inferred f...

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Many fibre-optic telecommunications systems exploit the spectral `window' at 1310 nm, which corresponds to zero dispersion in standard single-mode fibres (SMFs). In particular, several passive optical network (PON) architectures use 1310 nm for upstream signals,1 and so compact, low-cost and low-power modulators operating at 1310 nm that can be integrated into Si electronic-photonic integrated circuits would be extremely desireable for future fibre-to-the-home (FTTH) applications