10 Gbit/s silicon modulator based on carrier depletion in interdigitated PN junctions is experimentally demonstrated. The phase-shifter is integrated in a ring resonator, and high extinction ratio larger than 10 dB is obtained in both TE and TM polarizations. VπLπ of about 2.5 V × cm and optical loss lower than 1 dB are estimated. 10 Gbit/s data transmission is demonstrated with an extinction ratio of 4 dB.
Bragg filters stand as a key building blocks of the silicon-on-insulator (SOI) photonics platform, allowing the implementation of advanced on-chip signal manipulation. However, achieving narrowband Bragg filters with large rejection levels is often hindered by fabrication constraints and imperfections. Here, we present a new generation of high-performance Bragg filters that exploit subwavelength and symmetry engineering to overcome bandwidth-rejection trade-off in state-of-the-art implementations. We experimentally show flexible control over the width and depth of the Bragg resonance. These results pave the way for the implementation of high-performance on-chip pump-rejection filters with a great potential for Si-based quantum photonic circuits.
Silicon is the mainstream material in the electronic industry and it is rapidly expanding its dominance into the field of photonics. Indeed, silicon photonics has been the subject of intense research activities in both industry and academia as a compelling technology paving the way for next generation of energy-efficient high-speed computing, information processing and communications systems. The trend is to use optics in intimate proximity to the electronic circuit, which implies a high level of optoelectronic integration. Over the last decade, the field of silicon photonics has advanced at a remarkable pace. Most applicative sectors have now included silicon photonics in their roadmaps as a key technology to be deployed over short, medium or long-term horizons. This evolution towards silicon-based technologies is largely based on the vision that silicon provides a mature integration platform supported by the enormous existing CMOS manufacturing infrastructure which can be used to cost-effectively produce integrated optoelectronic circuits for a wide range of applications, including telecommunications, optical interconnects, medical screening, spectroscopy, and biological and chemical sensing… Recent advances and new trends in the development of silicon photonic devices will be presented.
The large transparency window of silicon (1.1 - 8 µm wavelength range) makes it a promising material for the implementation of a wide range of applications, including datacom, nonlinear and quantum optics, or sensing in the near- and mid-infrared wavelength ranges. However, the implementation of the silicon-on-insulator (SOI) platform in the mid-infrared is restricted by the absorption of buried oxide layer for wavelengths above 4 µm. A promising solution is to combine silicon membranes and subwavelength nanostructuration to locally remove the buried oxide layer, thus allowing access to the full transparency window of silicon. Additionally, structuring silicon with features smaller than half of the wavelength releases new degrees of freedom to tailor material properties, allowing the realization of innovative high-performance Si devices. Implementing Si membrane waveguides providing simultaneous single-mode operation at both near-infrared and mid-infrared wavelengths is cumbersome. Due to the high index contrast between Si and air cladding, conventional strip waveguides with cross-sections large enough to guide a mode in the mid-infrared are multi-mode in the near-infrared. Here, we exploit periodic corrugation to engineer light propagation properties of Si membrane waveguides allowing effective single-mode operation in near- and mid-IR. Single-mode propagation in the mid-IR is allowed by choosing a 500-nm-thick and 1100-nm-wide silicon waveguide. A novel waveguide corrugation approach radiates out the higher order modes in the near-IR, resulting in an effectively single-mode operation in near-IR. Based on this concept, we demonstrated Bragg filters with 4 nm bandwidth and 40 dB rejection.
The possibility of on-chip optical interconnects using rib waveguides on silicon-on-insulator substrates (SOI) is demonstrated. It is shown that ultrasmall (<0.4 μm 2 ) rib waveguides intrinsically combine the advantages of low measured propagation losses (<0.5 dB/cm), negligible crosstalk between waveguides and no crosstalk at right angle crossings. A set of devices have been studied using finite difference time domain analysis to realize 90° change of direction and beam splitting, including fully etched mirrors and 1×2 star couplers of 14 ×8-μm area. Considering the compactness and efficiency of all studied devices, it is shown that a compact and low-loss light distribution can be achieved in an integrated circuit toward at least 64 photodetectors with SOI rib waveguides that fully meets requirements of minimal power to be delivered to receiver circuitry.
We report on a nanostructured silicon resonator achieving optomechanical coupling between C-band photons and X-band phonons. We experimentally show the generation of 10GHz phonons, with decay rate of 3.49 MHz. This result opens new prospects for high-frequency silicon optomechanics with applications in communications, sensing and quantum-state control.
Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (−20 dB). A measured coupling efficiency of −2.7 dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.
