Lionel Camberlein

Single-mode rib optical waveguides on SOG/SU-8 polymer and integrated Mach-Zehnder for designing thermal sensors

This paper presents a successful design, realization,and characterization of single-mode rib optical waveguides on SOG/SU-8 polymers in order to highlight a new approach to designing heat sensors. The basic principle of this new thermal-sensing method relies on the differential thermal behavior regarding both acting arms of a micro Mach-Zehnder Interferometer(MZI). First, two families of single-mode straight rib waveguides composed of SOG/SU-8 polymers are analyzed. Hence, optical losses for TE00 and TM00 optical modes for structures on Si/SiO2/SU-8 have been estimated respectively as 1,36 plusmn 0,02 and 2,01plusmn0,02 dBmiddotcm-1, while the second one composed of Si/SiO2 /SOG/SU-8 presented losses of 2,33 plusmn 0,02 and 2,95plusmn0,02 dBmiddotcm-1. Then, owing to modeling results, an experimental sensor is realized as an integrated device made up of SU-8 polymer mounted on a standard silicon wafer. When subjected to a radiant source, as a laser light (980 nm) is injected across the cleaved input face of the MZI, the significant change of output signal allows us to consider a new approach to measuring radiant heat flowrate. Experimental results are given regarding the obtained phase shift against the subjected thermal power. According to the modeling results, one can expect new highly sensitive devices to be developed in the next coming years, with advantageous prospective industrial applications

Fast Psychrometers as New SU-8 Based Microsystems

In this paper, a new approach to designing fast micro-psychrometers devoted to measuring relative humidity is presented. Such devices are based on a planar thermopile fitted with an appropriate set of microchannels arranged for monitoring the evaporation process as a Seebeck voltage. They are fabricated out of a glass substrate, sputtered metals, and near vertical side walls made of SU-8, according to standard microtechnology processes for MEMs. Considering classical psychrometers, the new design is aimed at reducing both size and response time. Thus, besides being far less invasive than a standard unit, fast measurements (tau=5 s) are enabled. A straightforward modeling, aimed at deriving the relative humidity, is given with a view to integrating the signal conditioner. As regards validation, a prototype is calibrated and compared to a reference probe, and a discussion on its enhancement is also presented

Integrated Mach-Zehnder interferometer on SU-8 polymer for designing pressure sensors

This paper describes a new integrated pressure sensor based on a Mach-Zehnder (MZ) interferometer made of SU-8 polymer. Such a device is designed with a view to working in a standard intensity modulation scheme. To this end, the device takes advantage of a differential measurement thanks to a sensing arm of the MZ structure arranged upon a thin membrane actuated by the pressure to be dealt with, while the second arm allows for a reference signal. The combination of both signals out of the optimized structure of the interferometer allows us to detect any change in the optical path as a result of the applied pressure. A prototype is characterized by way of a specific optical bench allowing an efficient end-fire coupling into the sensor. Practical results prove such a design to delineate a promising measurement approach

A laterally coupled UV210 polymer racetrack micro-resonator for thermal tunability and glucose sensing capability

Authors report and demonstrate the feasibility of a laterally coupled racetrack microresonator based on UV210 photoresist to act as a thermal and glucose sensor. The large thermo-optic coefficient and the detection principle based on the interaction of the evanescent field with different glucose concentrations demonstrate that this sensor displays high sensitivity on detection properties. Deep-UV lithography procedures allow us to develop a laterally coupled microresonator with submicrometer patterns. The thermo-optic response of the racetrack microresonator is interrogated by using a NiCr alloy tip positioned on the top of the device. Temperatures ranging between 19 and 33°C yield a red shift of the resonant wavelength with a linear sensitivity of 220 pm °C− 1. Additionally, the thermal tunability is successively demonstrated by covering the resonator with DI water. A blue shift of the resonant wavelength is obtained with a linear sensitivity of 200 pm °C− 1. The resonance optical properties under this top cladding conditions lead a Q-factor of 4000 with a finesse of 5.7. Glucose homogeneous sensing capability is also experimentally demonstrated. Different concentrations of glucose solutions result in a red shift of the resonant wavelengths with a linear sensitivity of 280 pm mg− 1 ml− 1. Finally, these results validate the laterally coupled racetrack microresonator as an operative photonic component for integrated optical devices such as optical filters applied on telecommunication, or transducer components devoted to assess biochemical interactions. Graphical Abstract

Integrated optical Mach-Zehnder on SU-8 polymer for designing thermal sensors

A new approach to designing heat sensors is presented. The basic principle relies on the differential thermal behavior regarding both active arms of a micro Mach-Zehnder interferometer (MZI). Based on modeling results, an experimental sensor is realised as an integrated device made up of SU-8 polymer mounted on a standard silicon wafer. When subjected to a radiant source, such as laser light (980 nm), injected across the cleaved input face of the MZI, the significant change of output signal allows us to consider a new approach to measuring radiant heat flow rate. Experimental results are given regarding the obtained phase shift against the subjected thermal power. According to the modeling results, one can expect new highly sensitive devices to be developed in the next coming years, with numerous prospective industrial applications.

Metrological prospects for the assessment of transition plateaus

Heat flow transducers have been implemented within a thermometric fixed-point cell operated with indium. Then a local heat flow rate was monitored simultaneously with the classical temperature measurement. A specific configuration, so-called cell-within-cell, allowed us to control a melting transition plateau and to observe the behaviour of the heat exchanged during the whole process of the melting transition. Owing to their dynamic character, heat flow measurements prove to be the most appropriate for defining specific boundaries on a given transition plateau, and relevant sensors are found to be suitable tools to be coupled with enhanced temperature measurements. This piece of work is presented in two parts, with the description of the set-up and measurement results in this first paper and their subsequent thermodynamic implications in the following one.

A novel deep-UV polymer for integrated photonics: from waveguides structures to taper-waveguides coupled to cascade of multistage resonators used as thermal sensors

An overview of current research on integrated photonics based on the new UV210 phot-oresist is given. We report the overall design, fabrication and characterization of waveguides structures, multistage microresonators and their potential as thermal sensors.

Silica nano-ridges connections based on a fluidic approach for hybrid integrated photonics

We report a practical and novel concept based on reproducible fluidic mechanisms coupled with silica nano-particles for the development of nano-optical-connections directly on organic integrated photonic chips. Silica nano-rib waveguides have been shaped with various widths ranging between 50 nm and 300 nm and about a hundred μm in length respectively. An effective nano-photonic coupling mechanism has been demonstrated and a sub-wavelength propagation regime obtained between two organic rib tapers and waveguides with a perpendicular and a parallel configuration respectively. The specific silica nano-rib-waveguides structures show off optical losses propagation ranging around [37- 68] dB/mm at visible and infra-red (IR) wavelengths. Such flexible devices offer a versatile fabrication control by changing respectively nano-particles and surfactant concentrations. Thus, they present great potential regarding future applications for shaping nano-connections and high-density network integrations between original optical segmented circuits such as plots, lines or any pre-formed photonics structures.

Towards a thermodynamic assessment of transition plateaus

This second part of the work is devoted to the thermodynamic implications of the results presented in the preceding paper, as heat flow meters (HFMs) were installed within a thermometric fixed-point cell operated with indium. Then, simultaneous measurements of both temperature and heat flow allow us to pinpoint the specific boundaries (solidus and melt-off points) of a given transition plateau. To the best of our knowledge, this work is the first experimental illustration being reported on how to consider a plateau as a specific thermodynamic regime marked with a minimum amount of generated entropy in a metrological fixed-point cell. As a result, a significant relationship linking the boundaries of the plateau and the melting temperature of the material studied is presented. In order to obtain a quantitative understanding of the quality of a given transition process, straightforward thermodynamic considerations allow us to consider both theoretically and experimentally an adimensional parameter defined as the ratio of the entropy generation over the entropy change.

Characterization of the heat flux through the heat exchangers of a thermoacoustic cooler.

A small‐scale standing wave thermoacoustic cooler with a couple of stack and heat exchangers is studied. In addition to classical instrumentation in such a device, thermal heat flux sensors specifically developed using MEMS technology equipped the heat exchangers of this refrigerator. These sensors give the temporal evolution of the heat fluxes through the hot and the cold heat exchangers. Hence, they provide a better understanding of heat transfer between the stack and the heat exchangers. In this work, the temporal evolution of the temperature along the stack and of the heat flux through the heat exchanger is measured versus the acoustic pressure. The results show that for high‐pressure levels, the heat flux extracted at the cold exchanger rapidly increases until a maximum value and then stabilizes at a lower value. The origin of this limitation may come from the formation of vortices behind the stack highlighted in the work of Berson et al. [Heat Mass Transfer 44, 1015–1023 (2008)]. This work is suppor...