A high efficiency silicon nitride waveguide grating coupler with a multilayer bottom reflector

Abstract

We propose a high efficiency apodized grating coupler with a bottom reflector for silicon nitride photonic integrated circuits. The reflector consists of a stack of alternate silicon nitride and silicon dioxide quarter-wave films. The design, fabrication and optical characterization of the couplers has been presented. The measured fiber to detector insertion loss was −3.5 dB which corresponds to a peak coupling efficiency of −1.75 dB. A 3 dB wavelength bandwidth of 76.34 nm was demonstrated for the grating coupler with a 20-layer reflector. The fabrication process is CMOS-compatible and requires only a single etching step.

Review of Recent Progress on Silicon Nitride-Based Photonic Integrated Circuits

“…The TE00 mode is for C band coupling and TE01 mode for O band coupling. A bottom reflector based high efficiency apodized grating coupler with Si3N4 photonic integrated circuits is presented in [82]. Their single etch CMOS compatible design gives the measured peak coupling efficiency of -1.75dB and a 3dB wavelength bandwidth of 76.34 nm with a 20-layers of reflector.…”

“…Similarly, the peak coupling efficiency of -2.58 dB at 1576 nm with 1 dB bandwidth of 52 nm is obtained on the 400 nm thick silicon nitride. A low loss LPCVD based Si3N4 platform with a coupling loss of -6.5 dB at 1541 nm and 1 dB bandwidth of 55 nm was proposed in [82].…”

“…The Si3N4 platform alone and with III-V material has broadly been used for the polarization rotation and modulators [51][52][53][54][55], resonators and photodetectors [56][57][58][59][60][61][62][63][64][65], grating couplers [66][67][68][69][70], sensing applications [71][72][73][74], highperformance lasers on-chip, delay lines, optical filters, and optical frequency comb generation [75][76]polarization beam splitters and couplers [77][78][79][80]. The foundries all over the world, such as CEA-Leti, AIM photonics, ST microelectronics, and others have announced Si photonics as a platform that integrates Si3N4 waveguide layer onto Si waveguides for various applications [81][82][83][84][85][86][87].As the world is moving towards the high signal bandwidth and data rate, Si3N4 waveguide technology with SOI and III-V platform has recently opened up the new quarters for on-chip applications. This review paper has been addressing the importance of Si3N4 waveguide technology as an integration platform for silicon photonics.…”

Non-linear optical effects in cold and hot rubidium gases

“…These antennas can be used to connect the confined optical near-field to the free space optical far-field with a broadband operating range. Light can also be confined in dielectric waveguides, from which the connection to the far-field is often performed by surface grating coupling [11][12][13][14]. This technique is especially common practice in photonic integrated circuits [15].…”

“…Typically, surface grating couplers are addressed from the top and designed to operate at small angles of incidence. The large tolerance in acceptance angle, beam size and beam curvature make them convenient to use [14,[56][57][58]. Although generally addressed by a fibre in contact with the surface, the technique is also applicable to incoming beams of light.…”