Ultra-sharp asymmetric Fano-like resonance spectrum on Si photonic platform

In this paper, we report the generation of an ultra-sharp asymmetric resonance spectrum through Fano-like interference. This generation is accomplished by weakly coupling a high-quality factor (Q factor) Fabry–Pérot (FP) cavity and a low-Q factor FP cavity through evanescent waves. The high-Q FP cavity is formed by Sagnac loop mirrors, whilst the low-Q one is built by partially transmitting Sagnac loop reflectors. The working principle has been analytically established and numerically modelled by using temporal coupled-mode-theory (CMT), and verified using a prototype device fabricated on the 340 nm silicon-on-insulator (SOI) platform, patterned by deep ultraviolet (DUV) lithography. Pronounced asymmetric resonances with slopes up to 0.77 dB/pm have been successfully measured, which, to the best of our knowledge, is higher than the results reported in state-of-the-art devices in on-chip integrated Si photonic studies. The established theoretical analysis method can provide excellent design guidelines for devices with Fano-like resonances. The design principle can be applied to ultra-sensitive sensing, ultra-high extinction ratio switching, and more applications

Analysis of silicon germanium standards for the quantification of SiGe microelectronic devices using AES

Four samples of well-defined silicon-germanium alloys were used as standards for calibration purposes to allow accurate quantification of silicon-germanium-on-insulator (SGOI) microelectronic devices using Auger electron spectroscopy. Narrow Si KLL and the Ge LMM, high resolution Si KL2,3L2,3 and Ge L3M4,5M4,5 together with survey spectra were collected and are presented from each sample. A matrix effect was observed for silicon in germanium and calculated as 0.85 and 0.95 for the Ge77.5Si22.5 and Ge52.4Si47.6 alloys respectively

Silicon and germanium mid-infrared optical modulators

The mid-infrared wavelength region contains absorption fingerprints of numerous molecules and therefore is mostly considered for sensing applications [1]. However, due to a need for more spectral bandwidth for communications, and because modulation can be used to enhance signal to noise ratio in sensing applications, photonic modulator devices operating at mid infrared (MIR) wavelengths would be useful functional devices [2]. However, to date there have been few reported investigations of modulation in Si or Ge in the mid-infrared. SOI carrier injection modulators operating at up to 3 Gb/s with pre-emphasis at a wavelength of 2165 nm have been reported [3]. By using Ge rib waveguides with lateral p-i-n junctions, optical intensity modulation based on free-carrier absorption was demonstrated in Ge by injecting carriers through a Ge p-i-n junction at 1950 nm [4]. Also, thermo-optic modulation has been demonstrated in SOI at 3.8 μm [5], and in Ge-on-Si (GOS) and Ge-on-SOI (GOSOI) at ∼5.3 μm [6]. An all optical modulator based on free-carrier absorption has also been demonstrated in GOS with bandwidth of around 55 MHz across the 2-3.2 μm wavelength range [7]. In addition, two photon absorption (TPA) cross absorption modulation has been reported on the same platform and in the same wavelength range [8].</p

Ge-on-Si plasma enhanced chemical vapor deposition for low cost photodetectors

The development of low-thermal-budget Ge-on-Si epitaxial growth for the fabrication of low-cost Ge-on-Si devices is highly desirable for the field of silicon photonics. At present, most Ge-on-Si growth techniques require high growth temperatures, followed by cyclic annealing at temperatures &gt;800 °C, often for a period of several hours. Here, we present a low-temperature (400 °C) low-cost plasma-enhanced chemical vapor deposition (PECVD) Ge-on-Si growth study and, subsequently, fabricate a high-speed zero-bias 12.5-Gb/s waveguide integrated photodetector with a responsivity of 0.1 A/W at a wavelength of 1550 nm. This low-energy device demonstrates the feasibility of the PECVD method for the fabrication of low-cost low-thermal-budget Ge-on-Si devices

Group IV compounds for integrated photonic applications

We report methods of engineering the bandgap of SiGe and Ge compounds for the fabrication of electro absorption modulators and light emitting devices. We demonstrate uniform composition, single crystal, defect free SiGe-on-insulator formation. The composition can be tuned in different positions of the chip by modifying the structural design. We also demonstrate Ge disks with strain values of 1.1 and 0.6%

Nonconservative coupling in a passive silicon microring resonator

The authors report on nonconservative coupling in a passive silicon microring between its clockwise and counterclockwise resonance modes. The coupling coefficient is adjustable using a thermo-optic phase shifter. The resulting resonance of the supermodes due to nonconservative coupling is predicted in theory and demonstrated in experiments. This Letter paves the way for fundamental studies of on-chip lasers and quantum photonics, and their potential applications

25 Gbit/s silicon based modulators for the 2 µm wavelength band

We demonstrate high-speed silicon modulators optimized for operating at the wavelength of 2 µm. The Mach-Zehnder interferometer carrier-depletion modulator has a modulation efficiency (Vπ·Lπ) of 2.89 V·cm at 4 V reverse bias. It operates at a data rate of 25 Gbit/s with an extinction ratio of 6.25 dB

20-Gb/s silicon optical modulators for the 2 μm wavelength band

We demonstrate silicon-on-insulator based high speed modulators working at a wavelength of 1950 nm. The carrier-depletion Mach-Zehnder interferometer modulator operates at a data rate of 20 Gbit/s with an extinction ratio of 5.8 dB and modulation efficiency (Vπ Lπ) of 2.68 Vcm at 4 V reverse bias

Ion implantation in silicon for trimming the operating wavelength of ring resonators

In recent years, we have presented results on the development of erasable gratings in silicon to facilitate wafer scale testing of photonics circuits via ion implantation of germanium. Similar technology can be employed to control the operating wavelength of ring resonators, which is very sensitive to fabrication imperfections. Ion implantation into silicon causes radiation damage resulting in a refractive index increase, and can therefore form the basis of multiple optical devices. In this paper we discuss design, modelling and fabrication of ring resonators and their subsequent trimming using ion implantation of germanium into silicon, followed by either rapid thermal annealing or localized laser annealing. The results confirm the ability permanently tune the position of the resonant wavelength to any point inside the free spectral range of the ring resonator, thus greatly reducing the amount of power required for active tuning of these devices

Two-mode multiplexer based on the multilayer Si-SiN platform for 2μm waveband

We experimentally demonstrated a two-mode multiplexer in the multi-layer Si-SiN platform for 2µm waveband. The insertion loss of the mode multiplexer link is less than 2.2 dB across the wavelength 1945 nm-1985 nm