Compact packaged silicon photonic Bragg grating sensor based on a ball lens interface

Missinne, Jeroen; Geudens, Viktor; Put, Steven Van; Poulopoulos, Giannis; Szaj, Michal; Zervos, Charalampos; Avramopoulos, H.; Steenberge, Geert Van

doi:10.1016/j.optlastec.2022.108768

Cited by 9 publications

(15 citation statements)

References 25 publications

(20 reference statements)

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“…The fabrication technology employed for the realization of the sensor is a combination of femtosecond laser direct writing (FLDW) [20][21][22][23][24][25][26][27][28] and femtosecond laser irradiation followed by chemical etching (FLICE). [29][30][31][32][33][34][35] Mostly these technologies have been demonstrated separately, though a few papers combine them 36,37 Firstly, all structures (waveguides, Bragg gratings, contours of V-grooves and cantilever) are formed in a single laser exposure step. Next, the whole fused silica substrate is submerged in a KOH-solution for etching.…”

Section: Fabricationmentioning

confidence: 99%

Temperature compensated strain sensor in fused silica by femtosecond laser inscription

Geudens

Nategh²,

Steenberge³

et al. 2023

Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XVI

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Measuring strain without parasitic thermal influence is vital. A temperature compensated strain sensor is fabricated in fused silica using femtosecond laser micromachining. Utilizing femtosecond laser direct writing and femtosecond irradiation followed by chemical etching, two Bragg gratings are fabricated in the bulk of a fused silica substrate. By suspending one of the Bragg gratings in a cantilever, it is mechanically isolated from the rest of the substrate. Thermal and tensile characterization showed that both Bragg gratings are sensitive to thermal changes with a sensitivity around 10.5 pm/ • C, while only the non-isolated Brag grating is sensitive to strain with a sensitivity of 1.1 pm/µϵ. Hence, it is proven that the parasitic thermal influence on the strain sensor can be compensated by taking into account the response of the isolated Bragg grating.

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Section: Fabricationmentioning

confidence: 99%

Temperature compensated strain sensor in fused silica by femtosecond laser inscription

Geudens

Nategh²,

Steenberge³

et al. 2023

Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XVI

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“…A fused silica holder was created to assemble the ball lens at the precise distance with respect to either the fiber tip and PIC back side. Detailed optical interface design considerations and variations have been published in [4]. The results in the current paper were achieved using a 300 µm sapphire-based ball lens interface.…”

Section: Concept Of the Compact Silicon Photonic Sensor Probementioning

confidence: 99%

“…Compared to the lab setup described above, here a standalone commercial Bragg grating sensor interrogator (FBG-scan 608, FBGS, formerly FOS&S) was used with a lower power unpolarized source, explaining the weaker signals. We have previously determined the sensor transfer function using this test setup and found a linear sensor behavior between 15 and 60°C with a sensitivity of 73 pm/°C [4]. For the current publication, the fully packaged sensor was subjected to temperature cycling between 10°C and 180°C.…”

Section: Testing Of Assembled Sensorsmentioning

confidence: 99%

A fully packaged silicon photonic Bragg grating temperature sensor with a compact back side interface based on a ball lens

Missinne

Geudens

Put

et al. 2023

Silicon Photonics XVIII

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With the increased interest in silicon photonics, smart integration and packaging technologies are essential to transform photonic integrated circuits (PICs) into functional photonic systems. Especially for sensing, the currently existing standard packaging technologies are too expensive and bulky. We developed a solution for integrating a 1 mm x 1 mm sensor PIC with a single mode fiber and packaging it in a 1.5 mm inner-diameter metal protective tube. The concept relies on interfacing a grating coupler with a fiber from the back side of the PIC employing a 300 µm ball lens mounted in a laser-fabricated fused silica precision holder. It is shown that the additional insertion loss caused by the ball lens interface is very limited. A packaged sensor was achieved by sequentially mounting the holder on a ceramic ferrule, then the PIC on the holder and finally gluing a metal tube surrounding the assembly, taking care that the PIC surface is flush with the end face of the tube. The back side fiber interface ensures that the PIC's surface remains accessible for sensing, while the tube protects the fiber-to-PIC interface. We demonstrated this concept by realizing a packaged phase shifted silicon Bragg grating temperature sensor operating around 1550 nm, which could be read out in reflection using a commercial interrogator. A temperature sensitivity of 73 pm/°C was found, and we demonstrated sensor functionality up to 180°C.

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“…13 and 14, and a high-level overview of the packaging process was reported in Ref. 9. This paper expands on the latter, describing the packaging process in considerably more detail, especially focusing on the challenges associated with MPW PICs as starting components.…”

Section: Introductionmentioning

confidence: 99%

“…As an alternative not requiring postprocessing of the PIC, microball lenses have been used previously to couple laser diodes to grating couplers 8 . Although that approach interfaces the PIC from the device side, we proposed a solution in which we interface the PIC from the back side using a standard microball lens 9 and which only requires polishing and optionally antireflection (AR) coating of the PIC back side, which can more easily be done on MPW PICs.…”

Section: Introductionmentioning

confidence: 99%

Silicon photonic temperature sensor: from photonic integrated chip to fully packaged miniature probe

Missinne,

Geudens,

Poulopoulos

et al. 2023

J. Optical Microsystems

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With the increased interest in silicon photonics, integration and packaging technologies are essential to transforming photonic integrated circuits (PICs) into functional photonic systems. We describe in detail the process to obtain a fully packaged miniature photonic temperature sensor starting from bare PIC dies having Bragg grating sensors in a silicon waveguide. It is also shown that PICs fabricated via multiproject wafer services can show some variability, e.g., in the effective index, which has significant impact on the device functionality (Bragg wavelength) and optical interface (red-shifted grating coupler spectra at default coupling angles). To obtain a final sensor device that is as small as possible the PIC is interfaced from the back side using a 300 μm ball lens. Furthermore, this ensures that the top surface remains clear of any interfacing fibers. Based on this optical interfacing concept, we developed a solution for integrating a 1 mm × 1 mm sensor PIC with a single-mode fiber and packaging it in a 1.5 mm inner-diameter metal protective tube. The accurate position of the ball lens is ensured using a laser-fabricated fused silica precision holder. It is shown that the additional insertion loss caused by the ball lens interface is very limited. A packaged sensor was achieved by sequentially mounting the holder on a ceramic ferrule and then the PIC on the holder and finally gluing a protective metal tube surrounding the assembly, taking care that the PIC surface is flush with the end face of the tube. We demonstrated this concept by realizing a packaged phase-shifted silicon Bragg grating temperature sensor operating around 1550 nm, which could be read out in reflection using a commercial interrogator. A temperature sensitivity of 73 pm∕°C was found, and we demonstrated sensor functionality up to 180°C.

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Compact packaged silicon photonic Bragg grating sensor based on a ball lens interface

Cited by 9 publications

References 25 publications

Temperature compensated strain sensor in fused silica by femtosecond laser inscription

Temperature compensated strain sensor in fused silica by femtosecond laser inscription

A fully packaged silicon photonic Bragg grating temperature sensor with a compact back side interface based on a ball lens

Silicon photonic temperature sensor: from photonic integrated chip to fully packaged miniature probe

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