Thermally controlled coupling of a rolled-up microtube integrated with a waveguide on a silicon electronic-photonic integrated circuit

Abstract

We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up microtube and a waveguide on a silicon electronic-photonic integrated circuit. The microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the microtube and the waveguide using localized heaters, the microtube-waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0-6 V.

Integrative optofluidic microcavity with tubular channels and coupled waveguides via two-photon polymerization

“…A high deposition rate (3.0 Å s −1 ) and a 60°glancing angle were adopted during the SiO 2 layer deposition process to obtain a relatively low n (around 1.35), 19 which was lower than the refractive index (1.48) of the resist used and guaranteed the waveguide effect in our written structure. [51][52][53][54] After deposition, a fully integrated device, composed of a tubular microcavity with liquid reservoirs and a coupled waveguide, was directly fabricated by TPP (sketched in Fig. 5(a) with a top-view optical microscopy image shown in Fig.…”

Monolithically integrated self-rolled-up microtube-based vertical coupler for three-dimensional photonic integration

“…[7][8][9][10] The tube waveguide has been demonstrated both theoretically and experimentally to support whispering gallery modes (WGM) circulating along its circumference. 6,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] The light can be evanescently coupled between the tube and a straight waveguide once their separation is made adequately small, typically within a fraction of the wavelength of the propagating light. Several research groups have already demonstrated 3D photonic integration using the tube waveguide.…”

“…Several research groups have already demonstrated 3D photonic integration using the tube waveguide. 11,20,24,26 However, a monolithically integrated version of the tube waveguide to a planar ridge waveguide coupling has not yet been demonstrated experimentally. The result we report here is a monolithically integrated resonator-based vertical photonic coupler on silicon platform.…”

Demonstration of the first monolithically integrated self-rolled-up tube based vertical photonic coupler

“…Resonant coupling between the planar waveguide and the tube coupler can be clearly identified at discrete wavelengths. The highest extinction ratio is found to be about -23dB at 1558nm for device II, which is an order of magnitude higher than those observed in non-integrated tube to waveguide coupling experiments [2,3]. The spectral locations of the resonant peaks are slightly shifted between device I and II; this can be explained by the different axial confinement the light experiences when it is coupled into the tube coupler.…”

“…The self-rolled-up semiconductor tube is a good candidate for this application because it can be fabricated using planar processing techniques and functions as a 3D structure after self-assembly [1]. The self-rolled-up tube had been used to successfully couple light between waveguides [2,3]. But to monolithically integrate a vertical tube coupler and a planar waveguide has been an unsolved technical challenge.…”