title: All-optical phase modulation for integrated interferometric biosensors.
abstract: We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.
authors.affiliation: Research Center on Nanoscience and Nanotechnology CIN2 (CSIC) and CIBER-BBN, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Stefania
authors.initials: S
authors.lastname: Dante
authors.forename: Daphné
authors.initials: D
authors.lastname: Duval
authors.forename: Borja
authors.initials: B
authors.lastname: Sepúlveda
authors.forename: Ana Belen
authors.initials: AB
authors.lastname: González-Guerrero
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Sendra
authors.forename: Laura M
authors.initials: LM
authors.lastname: Lechuga
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D007368:Interferometry / Q000295:instrumentation*; D018511:Systems Integration