Silicon photonics is one of the most prominent technology platforms for integrated photonics and can support a wide variety of applications. As we move towards a mature industrial core technology, we present the integration of silicon nitride (SiN) material to extend the capabilities of our silicon photonics platform. Depending on the application being targeted, we have developed several integration strategies for the incorporation of SiN. We present these processes, as well as key components for dedicated applications. In particular, we present the use of SiN for athermal multiplexing in optical transceivers for datacom applications, the nonlinear generation of frequency combs in SiN micro-resonators for ultra-high data rate transmission, spectroscopy or metrology applications and the use of SiN to realize optical phased arrays in the 800–1000 nm wavelength range for Light Detection And Ranging (LIDAR) applications. These functionalities are demonstrated using a 200 mm complementary metal-oxide-semiconductor (CMOS)-compatible pilot line, showing the versatility and scalability of the Si-SiN platform.

Silicon carbide (SiC) exhibits promising material properties for nonlinear integrated optics. We report on a SiC-on-insulator platform based on crystalline 4H-SiC and demonstrate high-confinement SiC microring resonators with sub-micron waveguide cross-sectional dimensions. The Q factor of SiC microring resonators in such a sub-micron waveguide dimension is improved by a factor of six after surface roughness reduction by applying a wet oxidation process. We achieve a high Q factor (73,000) for such devices and show engineerable dispersion from normal to anomalous dispersion by controlling the waveguide cross-sectional dimension, which paves the way toward nonlinear applications in SiC microring resonators.

Silicon-nitride-on-insulator (SiNOI) is an attractive platform for optical frequency comb generation in the telecommunication band because of the low two-photon absorption and free carrier induced nonlinear loss when compared with crystalline silicon. However, high-temperature annealing that has been used so far for demonstrating Si3N4-based frequency combs made co-integration with silicon-based optoelectronics elusive, thus reducing dramatically its effective complementary metal oxide semiconductor (CMOS) compatibility. We report here on the fabrication and testing of annealing-free SiNOI nonlinear photonic circuits. In particular, we have developed a process to fabricate low-loss, annealing-free, and crack-free Si3N4 740-nm-thick films for Kerr-based nonlinear photonics featuring a full process compatibility with front-end silicon photonics. Experimental evidence shows that micro-resonators using such annealing-free silicon nitride films are capable of generating a frequency comb spanning 1300–2100 nm via optical parametrical oscillation based on four-wave mixing. This work constitutes a decisive step toward time-stable power-efficient Kerr-based broadband sources featuring full process compatibility with Si photonic integrated circuits on CMOS lines.

Frequency comb assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this letter we present a novel method using cascaded frequency agile diode lasers, which allows extending the measurement bandwidth to 37.4 THz (1355 -1630 nm) at MHz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy and in particular it enables to characterize the dispersion of integrated microresonators up to the fourth order.Frequency combs [1,2], providing an equidistant grid of lines with precisely known frequencies over a broad spectral range, have substantially advanced precision spectroscopy over the past decades. To date, diverse spectroscopic methods employing frequency combs have been invented, such as direct frequency comb spectroscopy [3], Fourier transform spectroscopy [4] and dual-comb spectroscopy [5]. Among these methods, frequency comb assisted diode laser spectroscopy [6], enabling broadband spectral characterization with fast measurement speed (> 1 THz/s) and simple implementation, has been successfully applied for distance measurement [7,8], dynamic waveform detection [9], plasma diagnostics [10] and molecular spectroscopy [11,12]. One application benefiting from these advantages is the dispersion characterization of high-Q microresonators [13][14][15][16][17], while alternative methods using direct frequency comb [18,19], white light source [20] or sideband spectroscopy [21] have several limitations including system complexity, low measurement speed, narrow bandwidth and inability to measure microresonators with free spectral ranges (FSR) exceeding 100 GHz.The dispersion characterization is important for the dispersion engineering of integrated high-Q microresonators for Kerr frequency comb generation [22,23] and bright dissipative Kerr soliton formation [24][25][26][27]. In addition, properly engineered higher order dispersion can lead to the emission of a dispersive wave via the process of soliton Cherenkov radiation [27][28][29][30]. Several techniques based on geometry variation [31] and additional material layers [13,32] have been demonstrated to tailor the dispersion. However, to measure the higher order dispersion of microresonators, frequency comb assisted diode laser spectroscopy is currently limited by its measurement bandwidth, which is mainly determined by the wavelength tuning range of the used laser. Therefore, using more than one laser to cover different spectral ranges is desired to overcome the bandwidth limitation thus en-OS

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