Silicon photonic waveguides for mid- and long-wave infrared region

Abstract

Silicon photonics is experiencing a dramatic increase in interest due to emerging application areas and several high profile successes in device and technology development (Liu et al Nature 427:615, 2004; Rong et al Nature 433:725, 2005; Almeida et al Nature 431:1081, 2004). Conventional waveguides in silicon photonics are designed for the telecom wavelengths. However, mid- and long-wave infrared regions are interesting for several application areas including sensing, communications, signal processing, missile detection and imaging (Soref et al J Opt A Pure Appl Opt 8:840, 2006). The most popular waveguide platform in silicon photonics is the Silicon-On-Insulator (SOI) structure, in the form of either a strip or a rib waveguide. This material structure, however, is not suitable for longer wavelengths (except in the 2.9-3.6 mu m range) due to the absorption spectra of silicon dioxide (Soref et al J Opt A Pure Appl Opt 8:840, 2006). In this paper, we discuss the design and fabrication of two different waveguide structures, the freestanding (Yang et al Appl Phys Lett 90:241109, 2007) and hollow core waveguides (Stankovi&Aumlaut double dagger et al Proceedings of 51th Conference ETRAN, 2007). The former is suitable for long-wave infrared applications as it has an air cladding, whilst the latter is a candidate for sensing in the mid-wave infrared wavelength region

Nonlinear optical response of low loss silicon germanium waveguides in the mid-infrared

“…Sensing applications require compact and low-cost optical devices and, most importantly, optical sources that are widely tuneable or yield broadband emission to access the whole mid-IR band. There have been a number of approaches, particularly within the silicon photonics community [3][4][5][6], to adapt technologies developed for the near-IR to the mid-IR for both linear [1,2,[7][8][9][10][11] and nonlinear photonic devices. For nonlinear devices, the issue of two-photon absorption (TPA) that limits device performance in the near-infrared region, vanishes at longer wavelengths (>2.2 μm) [1,3], and this has motivated some impressive nonlinear optical demonstrations in silicon on insulator (SOI) waveguides near 2 μm [7,10], as well as in silicon on sapphire (SOS) [11].…”

Low loss silicon waveguides for the mid-infrared

“…As the 3-5 μm wavelength range is interesting due to several application areas, the results presented here could lead to the realisation of a range of MIR integrated photonic circuits on SOI platform. We also investigate another potential candidate for longer wavelengths, a silicon-on-porous silicon waveguide [17][18][19][20]. First, the design and fabrication of the two waveguide structures are described, followed by the experimental technique used in this work.…”

Low propagation loss silicon-on-sapphire waveguides for the mid-infrared

“…Photonic integrated circuits for the mid-infrared (2-20μm) wavelength range is a new and burgeoning area of interest [1][2][3][4][5][6][7][8] for a variety of fundamental applications, including thermal imaging (2.5 -15μm) [9], chemical bond spectroscopy (from the visible to 20 μm and beyond), astronomy [10], gas sensing, and military applications such as missile countermeasures. Historically, however, the mid-infrared has posed challenges for photonics.…”

“…Recently, inexpensive and reliable single-mode quantum cascade lasers have become commercially available for wavelengths as long as 9 μm, and with powers from 10 -100 mW, and this has begun to change the landscape [11]. In addition, single-mode fibers are now available at wavelengths out to 6 μm [12,13], as are mid-infrared photodetectors with bandwidths over 1 GHz [6]. As a result, building a single-mode optical system in the mid-infrared is now within both financial and technical reach.…”