Silicon nitride photonics is on the rise owing to the broadband nature of the material, allowing applications of biophotonics, tele/datacom, optical signal processing and sensing, from visible, through near to mid-infrared wavelengths. In this paper, a review of the state of the art of silicon nitride strip waveguide platforms is provided, alongside the experimental results on the development of a versatile 300 nm guiding film height silicon nitride platform.

Photonic integration technologies have spread in the past decade by means of foundry models that mirror the electronic integrated circuit industry developments of the past century. Several monolithic technologies exist, based on silicon and III-V semiconductors. In this paper, we discuss the current state and forthcoming developments of open access photonic foundries whose technology platforms are based on silicon nitride material. The paper presents various silicon nitride technologies and foundries, alongside with access models supported by generic integration and process design kits. Technical features, enabled by different micro-fabrication processes and tools are summarized. Application examples and developments of forthcoming incorporation into these platforms are outlined.

A two-dimensional optical-phased array is demonstrated by using a multiple-input star coupler, compatible with FMCW LiDAR. Previous approach using a single-input design achieves two-dimensional beam-steering by relying on a tunable laser source, taking advantage of grating coupler radiation angle wavelength dependance and variation of the waveguide refractive index. While implementing a convenient way to distribute power in a single step, star coupler architecture is inefficient in terms of employed waveguide length and thus, optical loss and footprint. Multi-input approach partially alleviates this by condensing several single-input devices into one, permitting to reduce the footprint proportionally to the employed number of inputs. We fabricated in silicon nitride technology a proof of concept steerer with beam waist 0.36 $^\circ$ ×0.175 $^\circ$ addressing a field of view of 15 $^\circ$ ×2.8 $^\circ$ . A new design iteration is also reported with and 0.24 $^\circ$ ×0.16 $^\circ$ beam waist and 15 $^\circ$ ×11.2 $^\circ$ field of view. Implications of this optical-phased array chips from a LiDAR system perspective are also presented.

In this paper the concept and design of an integrated optical device featuring evanescent field sensing and spectrometric analysis is presented. The device, termed integrated optics sensing spectrometer (IOSS), consists of a modified arrayed waveguide grating (AWG) which arms are engineered into two sets having different focal points. Half of the arms are exposed to the outer media, while the other half are left isolated, thus the device can provide both sensing and reference spectra. Two reference designs are provided for the visible and near-infrared wavelengths, aimed at the determination of the concentration of known solutes through absorption spectroscopy.