Sub-wavelength grating components for integrated optics applications on SOI chips

Abstract

In this paper we demonstrate silicon on insulator (SOI) sub-wavelength grating (SWG) optical components for integrated optics and sensing. Light propagation in SWG devices is studied and realized with no cladding on top of the waveguide. In particular, we focused on SWG bends, tapers and directional couplers, all realized with compatible geometries in order to be used as building blocks for more complex integrated optics devices (interferometers, switches, resonators, etc.). Fabricated SWG tapers for TE and TM polarizations are described; they allow for connecting SWG devices to regular strip waveguides with loss lower than 1 dB per taper. Our SWG directional coupler presents a very compact design and a negligible wavelength dependence of its crossover length (and as a consequence of its coupling coefficient, κ), over a 40 nm bandwidth. This wavelength flatten response represents a bandwidth enhancement with respect to standard directional couplers (made using strip or rib waveguides), in particular for the TE mode. SWG bends are demonstrated, their loss dependence on radius is analyzed, and fabricated bends have a loss in the range 0.8-1.6 dB per 90 degrees bend. Simulated and measured results show promise for large-scale fabrication of complex optical devices and high sensitivity sensors based on SWG waveguides with engineered optical properties, tailored to specific applications.

Suspended Microracetrack Resonator with Lateral Sub-wavelength-Grating Metamaterial Cladding for Mid-infrared Sensing Applications

“…Many efforts have been invested on the SOI based bio-chemical sensing in the nearinfrared (NIR) band, typically around 1.3-1.6 µm wavelength [1][2][3][4][5][6]. Various structures and methods have been utilized to achieve high sensitivity [7][8][9][10][11][12][13][14][15][16][17][18]. However, limited work has been reported on mid-infrared (MIR) sensors based on the SOI platform.…”

Subwavelength grating devices in SOI

“…In the past few years, a variety of active and passive devices as well as integrated subsystems in CMOS-compatible silicon photonics platforms have been realized [2]. Subwavelength grating (SWG) waveguides have attracted interest due to their potential for low loss and flexibility in tailoring the effective index [3,4]. Indeed, a number of SWG-based devices/building blocks in silicon-on-insulator (SOI) have been developed, including waveguide crossings [3], bends [4], couplers [4][5][6], and ring resonators [7].…”

“…Subwavelength grating (SWG) waveguides have attracted interest due to their potential for low loss and flexibility in tailoring the effective index [3,4]. Indeed, a number of SWG-based devices/building blocks in silicon-on-insulator (SOI) have been developed, including waveguide crossings [3], bends [4], couplers [4][5][6], and ring resonators [7]. Bragg gratings (BGs) and ring resonators have important applications as optical filters and for implementation in more complex wavelength selective devices.…”

Subwavelength grating waveguide devices in silicon-on-insulators for integrated microwave photonics (Invited Paper)

“…Recently, there has been growing interest in realizing integrated optical components based on subwavelength grating (SWG) structures [8][9][10][11][12][13][14][15][16][17] . As illustrated in Fig.…”

“…These (SWG) tapers, depicted in Fig. 1(c), are based on a linearly chirped grating structure that has a uniform period P and where the waveguide width is narrowed in a linear manner from a width W 1 to W 2 over a length L taper [12] . In this paper, we review recent work on realizing basic building blocks based on SWG waveguides in SOI that can be used to implement more complex, integrated MWP signal processing engines.…”