Optofluidics is an emerging field in which photonics is combined with microfluidics to obtain inexpensive, flexible and reconfigurable devices for applications in many technological fields among which communications or biomedicals. An advantage of this approach compared to integrated electronic devices is a strong reduction of the power budget both in terms of energy dissipation and driving power. We present optical microchannels made of polydimethylsiloxane (PDMS) infiltrated with nematic liquid crystals (NLC) referred as LC:PDMS waveguides. An interesting feature of this optical channels is their polarization independence of light transmission at both visible and near infrared wavelengths. This solution allows the design and manufacture of switchable and tunable flexible devices by exploiting the electro-optical effects in LC. In this paper we also report the behavior of directional couplers based on LC:PDMS waveguides. The waveguides have a squared cross section of 2 µm x 2 µm. Oseen-Frank minimization of the free energy of the NLC within PDMS directional coupler was calculated using COMSOL Multiphysics, which provided the molecular orientation of the LC and the corresponding refractive index distribution inside the optical channels. This result has been implemented in BeamPROP, simulator of optical structures, to observe the directional couplers performance at the wavelength of 1550 nm. The LC has an extraordinary and ordinary refractive index respectively of 1.689 and 1.5, while the PDMS has a refractive index of 1.3997. From the simulations the ER, defined as the ratio between the power levels of outputs of the waveguides, was calculated. The ER varies as a function of the length and the gap of the directional couplers. [1] A. d’Alessandro, L. Martini, G. Gilardi, R. Beccherelli, and R. Asquini, “Polarization independent nematic liquid crystal waveguides for optofluidic applications,” IEEE Photonics Technology Letters, vol. 27, no. 16, pp. 1709-1712, 2015. [2] R. Asquini, L. Civita, L. Martini, A. d’Alessandro, “Design of Optical Directional Couplers Made of Polydimethysiloxane Liquid Crystal Channel Waveguides,” Mol. Cryst. Liq. Cryst, vol. 619, no. 1, pp. 12-18, 2015.
Simulations of Low Power Switches in LC:PDMS Waveguides for Optofluidic Applications / Civita, Luca; Asquini, Rita; D'Alessandro, Antonio. - STAMPA. - (2016). (Intervento presentato al convegno 1st International School of the IEEE Photonics Society - Italy Chapter, "Photonic Integration: advanced materials, new technologies and applications" tenutosi a E. Majorana Centre for Scientific Culture, Erice (Italy) nel 25th September - 1st October 2016).
Simulations of Low Power Switches in LC:PDMS Waveguides for Optofluidic Applications
Civita, Luca;ASQUINI, Rita;D'ALESSANDRO, Antonio
2016
Abstract
Optofluidics is an emerging field in which photonics is combined with microfluidics to obtain inexpensive, flexible and reconfigurable devices for applications in many technological fields among which communications or biomedicals. An advantage of this approach compared to integrated electronic devices is a strong reduction of the power budget both in terms of energy dissipation and driving power. We present optical microchannels made of polydimethylsiloxane (PDMS) infiltrated with nematic liquid crystals (NLC) referred as LC:PDMS waveguides. An interesting feature of this optical channels is their polarization independence of light transmission at both visible and near infrared wavelengths. This solution allows the design and manufacture of switchable and tunable flexible devices by exploiting the electro-optical effects in LC. In this paper we also report the behavior of directional couplers based on LC:PDMS waveguides. The waveguides have a squared cross section of 2 µm x 2 µm. Oseen-Frank minimization of the free energy of the NLC within PDMS directional coupler was calculated using COMSOL Multiphysics, which provided the molecular orientation of the LC and the corresponding refractive index distribution inside the optical channels. This result has been implemented in BeamPROP, simulator of optical structures, to observe the directional couplers performance at the wavelength of 1550 nm. The LC has an extraordinary and ordinary refractive index respectively of 1.689 and 1.5, while the PDMS has a refractive index of 1.3997. From the simulations the ER, defined as the ratio between the power levels of outputs of the waveguides, was calculated. The ER varies as a function of the length and the gap of the directional couplers. [1] A. d’Alessandro, L. Martini, G. Gilardi, R. Beccherelli, and R. Asquini, “Polarization independent nematic liquid crystal waveguides for optofluidic applications,” IEEE Photonics Technology Letters, vol. 27, no. 16, pp. 1709-1712, 2015. [2] R. Asquini, L. Civita, L. Martini, A. d’Alessandro, “Design of Optical Directional Couplers Made of Polydimethysiloxane Liquid Crystal Channel Waveguides,” Mol. Cryst. Liq. Cryst, vol. 619, no. 1, pp. 12-18, 2015.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
