AP Technologies will be exhibiting the latest developments in Silicon Photomultipliers and Liquid Crystal optical components at Photonex. To support these APT is also taking part in the Photonics Tutorials on Wednesday 14th October.

Dr. Fredrik Kihlborg, R&D Manager at LC-Tec will discuss their Liquid Crystal fast optical shutter, fast polarisation modulator and variable filter technology at 1120 whilst Martin Sharratt will present SensL Technologies’ silicon photomultiplier (SiPM) technology at 1240.

Fig. 1: Liquid Crystal Fast Optical Shutters

Dr. Fredrik Kihlborg, R&D Manager at LC-Tec is presenting “Liquid crystal-based optical components and their applications”.

Liquid crystals are materials in a phase in between a liquid and a solid crystal. They consist of rod-shaped molecules that are ordered, making the material birefringent. At the same time the molecules can move with respect to each other and their orientation can be controlled by an applied electric field. This gives the possibility to use liquid crystals to modulate the properties of light passing through them. Product examples include fast optical shutters, variable neutral density filters, tuneable colour filters, polarisation modulators, and variable phase retarders.

Fredrik’s talk gives an introduction to the technology behind optical components based on liquid crystals and discusses application areas where these components are commercially exploited.

LC-Tec’s Liquid Crystal Fast Optical Shutter (FOS) products replace conventional beam choppers with compact, planar, low voltage and vibration-free devices with no moving parts. The FOS consists of a liquid crystal polarisation modulator positioned between crossed linear polarisers. Applying a drive voltage reorients the birefringent LC molecules resulting in a change in transmittance of the light passing through the full shutter structure meaning it is also possible to achieve analogue grey-scale operation between fully-open and fully-closed states.

The patented PolarSpeed® product offers unprecedented 30µs symmetrical switching.

LC-Tec can also supply Liquid Crystal Fast Polarisation Modulator (FPM) devices enabling switching between two output polarization states, for example between linear-linear or left- and right-handed circular polarisation. Major applications include 3D-projection where LC-Tec’s technology can be found in 3D cinemas worldwide.

Other applications include 3D displays, cameras and microscopes where LC-Tec’s low wavefront aberration performance maintains excellent image quality.

LC-Tec produce their FOS and FPM products using 14” by 16” starting sheets so can produce extremely large devices when required.

Fig. 2: 6mm SiPM mounted on evaluation board.

Titled “SensL Technologies introduce a new generation of silicon photomultipliers” Martin’s presentation is sub-titled “So you think you know SiPMs” – a reference to the fact that the performance of SensL’s SiPMs has evolved at a phenomenal rate over the past few years.

Martin will discuss principles of operation including SensL’s patented “fast-mode” and highlight key criteria which customers should consider when deciding which SiPM is the best choice for their system.

The presentation will briefly discuss the evolution of Dark Count Rate (DCR) and Photon Detection Efficiency demonstrating ~1000-fold increase in SNR since 2010. Manufacturing flow, product uniformity and the results of JEDEC-based reliability testing is also presented – leading into a discussion of the performance of SensL’s newly expanded product range.

SensL are introducing two new designs of SiPM – bringing their range to three distinct families:-

C-series: 1mm, 3mm and 6mm, high-volume & low-cost, high PDE with ultra-low DCR technology introduced in 2014. The C-series remains the core product and is expected to continue to meet the requirements of most customers.

J-series: These 3mm and 6mm active area SiPMs maintain the DCR performance of the C-series with higher PDE and dramatically improved timing performance. The J-series introduces SensL’s revolutionary wafer-scale Through Silicon Via glass SMT packaging technology which significantly reduces the package footprint – enabling much higher 2D array packing.

R-series: Red-enhanced 1mm SiPMs achieving peak PDE at ~620nm and 530kA/W responsivity at 900nm (35µm microcells) the J-series is SensL’s solution for the 3D Imaging and Sensing market using LiDAR techniques.

Fig. 3: J-series 6mm SiPM showing high performance Through Silicon Via (TSV) package.

SensL’s J-series introduces their revolutionary wafer-scale Through Silicon Via (TSV) glass package. This leading-edge packaging technology is available as a direct result of SensL’s “fabless” philosophy which enables them to partner with world-leading 200mm CMOS wafer fabs. Developed for CMOS imaging sensors used in the mobile phone market no other SiPM or photodiode manufacturer has access to this technology.


As well as enabling a much more compact package footprint of just 3.16mm and 6.13mm, compared to 4mm and 7mm, TSV brings benefits in terms of the short wavelength transmission and operating temperature. TSV also enables changes to the readout architecture, improving timing performance of the J-series SiPMs which achieve standard mode rise times of <<1ns with microcell recovery times reduced to ~100ns.


Please visit APT on Stand A11 to see an LC-TEC FOS in action and discuss your SiPM, laser diode, LED and detection requirements.