For miniaturized optical fiber coupled MOEMS systems, fiber coupling on chip level is necessary. Therefore a silicon chip based optical fiber coupling with high position accuracy is introduced. In this paper, we present the fiber chip coupling on two examples: A superconducting single photon detector (SSPD) and a miniaturized fiber Bragg grating sensor. In case of the SSPD position accuracy between SSPD and optical fiber of ± 1 μm is necessary.
In this paper we show the developed alignment system and the proof of the position accuracy on silicon test chips. Further, we show first experiments of a fiber coupled superconducting test structure in a closed cycle cryostat with regard to stability of the chip stack and thermal connectivity to the cryostat.
The fiber coupling of the fiber Bragg grating sensor is used to miniaturize the sensor overall construction. The fiber Bragg sensor consists of two stacked Silicon photodiodes. The top photodiode is fabricated in a cavity within a remaining 50 μm Silicon membrane and therefore detects only the shorter wavelength range. The bottom photodiode detects the transmitted longer wavelengths. The fiber coupling chip is mounted on top of the photodiode stack. This leads to a compact chip stack with included fiber coupling, without the need for large fiber connectors or ferrule holders. Further, we demonstrate the mounting of the fiber Bragg sensor on a flexible PCB and its performance.
Fluorescence lifetime determination is widely utilized for bioscience research and analysis. The fluorescence stimulation in conventional systems is usually done with expensive picosecond laser systems. We present a cost-effective 370 nm LED based excitation module and a detection unit based on a Silicon Photomultiplier (SiPM). The functionality of the excitation module as well as the detection module is demonstrated with the fluorescence dye ATTO 390.
For a fast analysis of the fluorescence signal detected by the SiPM, we developed an ASIC for fluorescence histogram recording. The ASIC determines the time between excitation pulse and incoming fluorescence photon with an accuracy of about 80 ps. The ASIC blind time after the excitation pulse is configurable. The determined time is saved in bins. The width of the bins is programmable. Output of the ASIC is a histogram with the counted amount of photons at the different times after excitation. This histogram equals the fluorescence response of the dye. The fluorescence lifetime can be calculated out of this histogram.
Fluorescence lifetime determination is widely utilized for bioscience research and analysis. The fluorescence stimulation in conventional systems is usually done with expensive picosecond laser systems. We present a cost-effective 370 nm LED based excitation module with a pulse FWHM of 1 ns and a beam diameter of 4 mm. The functionality of the excitation module was demonstrated with the fluorescence dye ATTO 390 with a fluorescence lifetime of 5 ns. The width of 8 mm of the excitation module enables the parallel measurement of adjacent sample chambers of a well plate. Further, a silicon UV-photodiode is designated to monitor the output power of the LED. For a fast analysis of the fluorescence signal, we developed an ASIC for fluorescence histogram recording. The ASIC determines the time between excitation pulse and incoming fluorescence photon with an accuracy of about 80 ps. The ASIC blind time after the excitation pulse is configurable. The determined time is saved in bins. The width of the bins is programmable. For fluorescence light detection a silicon photomultiplier (SiPM) is used. Output of the ASIC is a histogram with the counted amount of photons at the different times after excitation. This histogram equals the fluorescence response of the dye. The fluorescence lifetime can be calculated out of this histogram.
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