TY - JOUR
T1 - Silicon nitride directional coupler interferometer for surface sensing
AU - Okubo, Kyohei
AU - Uchiyamada, Ken
AU - Asakawa, Kiyoshi
AU - Suzuki, Hiroaki
N1 - Funding Information:
They also thank Masatoshi Yokokawa, Edwin T. Carlen, and Yasuhiro Horiike for their support and cooperation. This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant No. 25286034. K.O. thanks the JSPS Research Fellowships for Young Scientist (Project No. 16J03567) for financial support.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - A silicon nitride directional coupler (DC) used to create a biosensing device is presented. The DC detects changes in the refractive index of the cladding (nclad) as changes in the relative output intensity. The DC length (L), nclad-dependent sensitivities of the DC, and preferred dimensions of the single-mode DC waveguides are obtained through numerical simulations. The performance of the DC is evaluated through end-fire coupling measurements. The intensities measured after varying the nclad using air, water, and glycerol solutions agree well with the fitting for a wide range of L values between 60 and 600 μm, i.e., corresponding to 6 to 60 times the coupling length. The bulk refractive index sensitivity was investigated using glycerol solutions of different concentrations and was found to be 18.9 optical intensity units per refractive index unit (OIU/RIU). Biotin/streptavidin bindings were detected with a sensitivity of 60 OIU/RIU and a detection limit of 0.13 μM, suggesting the feasibility of the DC for immunosensing.
AB - A silicon nitride directional coupler (DC) used to create a biosensing device is presented. The DC detects changes in the refractive index of the cladding (nclad) as changes in the relative output intensity. The DC length (L), nclad-dependent sensitivities of the DC, and preferred dimensions of the single-mode DC waveguides are obtained through numerical simulations. The performance of the DC is evaluated through end-fire coupling measurements. The intensities measured after varying the nclad using air, water, and glycerol solutions agree well with the fitting for a wide range of L values between 60 and 600 μm, i.e., corresponding to 6 to 60 times the coupling length. The bulk refractive index sensitivity was investigated using glycerol solutions of different concentrations and was found to be 18.9 optical intensity units per refractive index unit (OIU/RIU). Biotin/streptavidin bindings were detected with a sensitivity of 60 OIU/RIU and a detection limit of 0.13 μM, suggesting the feasibility of the DC for immunosensing.
KW - directional coupler
KW - interferometry
KW - silicon nitride waveguide
KW - streptavidin detection
UR - http://www.scopus.com/inward/record.url?scp=85009267041&partnerID=8YFLogxK
U2 - 10.1117/1.OE.56.1.017101
DO - 10.1117/1.OE.56.1.017101
M3 - Article
AN - SCOPUS:85009267041
VL - 56
JO - SPIE J
JF - SPIE J
SN - 0091-3286
IS - 1
M1 - 017101
ER -