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On-chip mid-infrared (mid-IR, from 3 to 15 μm wavelength) supercontinuum (SC) generation is of great interest for integrated sensing devices, since it enables parallel detection of multiples species [1] . The generation of mid-IR SC in group IV platforms is particularly significant, since it would allow low-cost, large-scale production and electro-optic integration. Mid-IR SC generation has been demonstrated in several group-IV platforms [1] – [4] . Recently, the wide transparency window up to 15 μm and theoretical predictions of attractive nonlinear properties [5] led researchers to explore germanium as a promising material for mid-infrared photonics. However, experimental SC generation in pure germanium waveguides remained elusive so far. Our group reported SC generation up to 8.5 μm in silicon-germanium on silicon waveguides [3] . We have also demonstrated the possibility, with this platform, of precisely controlling the SC coherence properties [6] – [8] . The great potential of germanium-based platforms for on-chip mid-IR SC generation was recently confirmed, with the demonstration of a SC extending from 3 up to 13 μm in a germanium-rich graded index silicon-germanium on silicon waveguide [9] . To achieve such a broad spectrum, however, the waveguide was pumped at 7.5 μm, whereas short wavelength pumps are preferable in fully integrated broadband sources.

A high-sensitivity multiplicative analog complex correlator is designed to meet the medical requirement of measuring the human body temperature by adopting millimeterwave radiometer technology. The analog complex correlator adopts phase shifter to calibrate the phase deviation of the two input signals in order to improve the precision of temperature measurement. Compared with the traditional scheme of the diode square law detector, this paper tries to adopt quadrature demodulator to accomplish the detecting function. The result indicates that the detection sensitivity improves 3.478 times and the bandwidth increases to 5.5 GHz, in addition, the structure of the circuit is simplified. The experimental results show that the sensitivity of the analog complex correlator can reach 173 mV / dBm when the input power is in the range of 7dBm to 8dBm. When the human body temperature is in the range of 330oC to 43o C, the precision can reach ± 0.331 o C. Having the phase error, offset error and gain error calibrated by software algorithm, the analog complex correlator can reach the level of medical measurement.

Storing and delaying optical information is of crucial importance for optical communications, signal processing and in the quantum domain. A plethora of techniques for optical storage have been shown which aim to maintain as much as possible the advantages of optics, such as e.g. the coherence, the bandwidth and capacity. In particular the interaction of optical waves with mechanical motion offers a solution to buffer optical information [1–4]. It was shown that one can use acoustic waves to store and delay optical signals coherently via the effect of stimulated Brillouin scattering (SBS) [3,4]. This allows for simultaneous storage at multiple wavelengths [5], cascaded storage at different spatial positions [6], and nonreciprocal storage with a GHz bandwidth [7]. However, the delay time of this technique is so far limited to the acoustic lifetime of about 10 ns.

Phase shifters are an important building block of modern RF communications and RADAR systems, with an ever increasing demand to improve the operating bandwidth and to reduce power consumption and footprint. Microwave photonic phase shifters based on stimulated Brillion scattering (SBS) offer tunable and broadband phase shifts, however, their performance has been constrained by the requirement of high Brillouin gain to achieve 360° of phase shift. Here, we demonstrate a 360° broadband phase shifter by combining SBS and RF interference which greatly reduces the required Brillouin gain and thus the required optical power. Using this technique, we are able to enhance the phase shift by more than an order of magnitude, showing bandwidth tunability from 0.1-65 GHz while also being optimized to minimize amplitude variations.

We present our recent results on harnessing the nonlinear stimulated Brillouin scattering effect on a photonic chip for coherent optical communications. At the transmitter-end, an optical frequency comb was regenerated through on-chip Brillouin scattering for 64-level QAM communications. At the receiver-end, low-latency self-homodyne reception was achieved through Brillouin-assisted carrier recovery.

We demonstrate the first all-optical carrier recovery of coherent signals using on-chip Brillouin gain, replacing digital techniques, with sub-nanosecond latency. This demonstration serves as a proof-of-concept for integrated photonic carrier recovery chips for coherent communications.

We store optical data in acoustic waves on a planar waveguide based on stimulated Brillouin scattering (SBS) and demonstrate for the first time that this coherent light storage concept allows for the simultaneous storage at different frequency channels, separated by 100 GHz, without observable cross-talk between the individual channels.

We for the first time, study the effect of signal power variations on the extinction ratio and bandwidth of on-chip Brillouin filters for applications in RF photonics and coherent optical communications. The passband extinction reduces from 35 dB to 25 dB on increasing the input signal power by 36 dB, while the bandwidth increased from 13 MHz to 30 MHz.

Stimulated Brillouin scattering (SB S) is a strong nonlinear interaction between the incident pump photons and the acoustic phonons in a guiding structure [1]. This results in the scattering of light from the pump field to the Stokes field which is frequency-shifted by ∼10 GHz. SBS has been extremely useful in a number of applications: ultra-narrow bandwidth laser, sensing, slow and fast-light, microwave signal processing, and ns scale light signal storage [2]. A number of geometries that can be used to harness SBS such as fibers, embedded waveguides, suspended waveguides and resonators in various materials such as silica, chalcogenide, silicon, calcium fluoride [2]. Off all the platforms, As2S3 waveguide devices have been demonstrated to be the most suitable for integrated efficient SBS [3]. While silicon offers CMOS compatibility, it suffers from multiphoton absorption and free-carrier absorption, which affects the SBS performance [4]. Furthermore, extra processing is required for fabricating suspended nanowires, which makes it hard to make longer lengths [5]. Chalcogenide glasses have demonstrated both large Kerr and SBS nonlinearity and very low two photon absorption at 1.5μm pump. Previously, the SBS gain of 23dB in As2S3 was reported [3]. In addition, chalcogenide waveguides can be fabricated on a CMOS compatible platform could result in a hybrid chalcogenide-silicon platform for enabling opto-electronic integration of applications based on SBS and Kerr nonlinearity [6].

Storing light as coherent sound waves is an intriguing and powerful concept for delaying optical signals. It was shown that optical data pulses can be transferred to acoustic waves in optical fiber [1] and, more recently, in integrated circuits [2]. The coupling between the optical and acoustic waves has to fulfill a strict phase matching condition, which was exploited in silica fiber-tip resonators to realize non-reciprocal signal processing [3, 4].

An optical frequency comb can generate hundreds of individual comb lines which can be employed in wavelength division multiplexing systems [1], thus reducing the cost, footprint, power consumption and system complexity when compared to using multiple lasers. However to date, comb-based communications have been limited to lower modulation formats more tolerant to phase noise, due to poor carrier to noise ratios resulting from high parametric noise in the comb. We recently proposed a technique [2], to regenerate a C-band optical frequency comb for transmission of 64 QAM signals. This was based on using a narrowband (∼10 MHz) amplifier generated through stimulated Brillouin scattering (SBS) in a 4.46-km standard single mode fibre to significantly suppress noise around the carrier thus increasing the carrier to noise power ratio. In this work, we present the regeneration of a C-band 40-GHz comb using SBS on a photonic chip, reducing the length of the SBS medium by more than 4 orders of magnitude and paving the way towards photonic integration and low-cost manufacturing. This work also represents the first-ever implementation of on-chip SBS in high-speed optical communications.

Mg-doped colloidal silica abrasive was synthesized by seed-induced growth method. A detailed analysis was presented to characterize the composition and morphology of Mg-doped colloidal silica abrasive by using time-of-flight secondary ion mass spectroscopy and scanning electron microscopy. The chemical mechanical polishing performances of the Mg-doped colloidal silica abrasive on silicon wafer were investigated. Experimental results indicate that Mg-doped colloidal silica abrasive exhibits higher material removal rate and lower surface roughness than pure colloidal silica abrasive under the same polishing conditions.

JUN 28-JUL 02, 2015; International audience; The mid-infrared is of great interest for a huge range of applications such as medical and environment sensors, security, defense and astronomy. I will give a broad overview of the different activities recently launched in INL Lyon, in close collaboration with several French and Australian institutions, under the umbrella of ``Mid-IR integrated photonics” with a particular focus on novel integrated sources for the Mid-IR exploitinga nonlinearSiGe platform

We report the low-loss chalcogenide waveguides for bio sensing in the mid-infrared (MIR), which consisted of a Ge 11.5 As 24 Se 64.5 rib waveguide core on a magnesium fluoride crystalline substrate. The losses were

We have produced ≈20mW of mid-infrared super continuum spanning from 1750nm to ≈8000nm spanning using a 1cm long chalcogenide waveguide pumped by a 21MHz train of 320fs pulses at 4μm.

In this work, we present the first experimental report validating the potential offered by SiGe/Si waveguides in the mid-IR with record low propagation loss over a wide bandwidth, which range between 1.5 dB/cm @3.25 μm down to 0.5 dB/cm @ 4.75 μm.

By analyzing the data obtained by GPS in dynamic deformation, processing analog GPS data mixed with random interference in the experiments through adopting various wavelet functions and different rank of the wavelet, and contrasting their analysis results, the suitable Daubechies function with the 'N' of six (db6) could be found. And it was used to filter GPS data of dynamic deformation, distill deformation character and separate different deformation frequency. From the processing results of actual data for large dam, we can realize db6 wavelet is advantaged to improve GPS data accuracy of dynamic deformation and its effect is notable.