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Picophotonics, a spin-off from the Optoelectronics Research Centre at the Tampere University (Finland), focuses on the development and manufacturing of Q-switched microchip lasers based on proprietary semiconductor saturable absorber mirror (SESAM) technology. The company's mission is to provide a laser platform bridging the gap between the parameters offered by the more complex mode-locked lasers delivering picosecond pulses, and conventional Q-switched lasers operating in the ns region.

EPIC's Jose Pozo spoke with Picophotonics CEO, Antti Penttinen, and learned that his path began when he was in the first year of a BSc in Natural Sciences and Engineering at Tampere University in Finland, and Antti worked as a research assistant at Optoelectronics Research Centre (ORC), where he specialized in laser physics. While finishing up with his MSc, Antti started as the CEO of Picophotonics, a spin-off from the ORC, which has been set up to develop and manufacture Q-switched microchip lasers based on proprietary semiconductor saturable absorber mirror (SESAM) technology.

Antti Penttinen

As he explains, Picophotonics Oy had been founded in 2015 by Prof. Mircea Guina (Chairman and CSO of the company) and Dr. Antti Härkonen (CTO). They were working on several early phase prototypes while planning for expanding the core team, in particular to cover the business development needs. Following in the footsteps of his elder brother, Jussi-Pekka, one of the founders and CEO of the VECSEL technology company Vexlum - also a spin-off from Tampere’s ORC - Antti was confident he could rise to the challenge.

The technology

Picophotonics lasers use in-house developed semiconductor-based absorber technology (SESAM) for passive Q-switching. The signal can be further amplified in a simple master oscillator – power amplifier (MOPA) configuration that does not affect the spectral or temporal properties of the laser.

SESAM

The main advantage of this approach is that it enables a significant reduction of the pulse width at relatively high repetition rates, while keeping the simple and robust microchip laser architecture. The pulse duration can be tailored from below 100 ps at 1064 nm to 0.5 – 5 ns range at 1535 nm. Compared with traditional Q-switched lasers, Picophotonics lasers offer much higher repletion rate, up to MHz region. Moreover, owing to the relatively short pulse duration in the range of 100 ps, the laser can provide high peak power without amplification, at both 1064 nm and 1535 nm. In terms of pulse energy, over 10 µJ at 1535 nm can be obtained directly from a very compact seed laser that can be battery-operated. Moreover, the single-frequency output has a narrow spectral width Δλ < 0.15 nm. The narrow spectral width and high peak power enable efficient single-pass frequency to 532 nm, 355 nm and 266 nm. Other wavelengths, such as 573 nm, 620 nm, 1240 nm etc. can be also obtained.

Products & applications

Over the last three years, Picophotonics team has developed a range of compact lasers and cost-effective solutions for various applications, including LIDAR and range-finding as well as spectroscopy and microscopy. The prototypes already deployed to applications or in testing phase include:

532 nm, 100 ps, high-power MOPA laser system. With a pulse duration of 50 ps – 200 ps, a repetition rate of 10 kHz – 200 kHz, pulse energy from 0.5 µJ – 2 µJ, and a peak power of 5 kW with 200 kHz, 10 kW with 100 kHz, >15 kW with 50 kHz, this laser is ideal for applications such as photoacoustic microscopy, time-gated spectroscopy, and fluorescence lifetime imaging.

767 nm compact laser source. pulse duration <1 ns – 5 ns; repetition rate 1 kHz – 100 kHz; pulse energy 0.1 µJ – 3 µJ; peak power 100 W @ 100 kHz, 500 W @ 50 kHz, 2 kW @ 10 kHz. Applications include LiDAR, medical imaging, spectroscopy, and photo-acoustic microscopy.

1064 nm, 100 ps high-power MOPA laser. Pulse duration 50 ps – 200 ps; repetition rate 10 kHz – 200 kHz; pulse energy 2 µJ – 6 µJ; peak power 15 kW @ 200 kHz, 25 kW @ 100 kHz, >40 kW @ 50 kHz. Applications: multiphoton processes, photo-acoustic microscopy, and material processing.

1064 nm, 100 ps seed laser:

seed laser

Pulse duration 50 ps – 200 ps: repetition rate 10 kHz – 200 kHz; peak power 0.6 kW @ 200 kHz, 1.0 kW @ 100 kHz and 1.5 kW @ 50 kHz. Applications: seeding fiber amplifiers.

Compact eye-safe, 1535 nm laser: pulse duration 1 ns – 10 ns; repetition rate 1 kHz – 500 kHz; pulse energy 0.1 µJ – 10 µJ, peak power           50 W @ 500 kHz, 1 kW @ 100 kHz, 3 kW @ 10 kHz, 8 kW @ 1 kHz.  Applications: LiDAR & range-finding.

The future

Antti is optimistic about the future because their products enable compact and cost-effective laser solutions, with economy of scale volume manufacturing. The use of SESAM technology offers a unique combination of parameters and customization means. Having also in-house expertise on laser physics, optics and mechanical design, as well as electronics and automation, Picophotonics is poised to provide disruptive solutions for several emerging markets requiring more practical high energy laser pulses.

RAMAN spectroscopy: the 532 nm < 100 ps MOPA systems have proved instrumental for advance time-gated RAMAN spectroscopy systems used in a wide range of applications.

Lidar and range-finding: these applications benefit from the high repetition rates, required to achieve a high accuracy and resolution of imaging. These can be achieved with our SESAM-based lasers while delivering also high pulse energy from a very compact package. To this end we have developed a product line emitting at 1535 nm, a region where the power limits for eye-safety are relaxed.

Seed lasers: Growth in the fiber amplifier segment is driving the demand for seed lasers with high energy and short pulse duration, which Picophotonics is addressing with the own 1064nm, <100 ps product line. The company intends to continue trials for different options with the aim of extending their offer for this type of laser, in particular with shorter pulses.

Medical applications: The 767 nm wavelength is particularly useful for medical applications. Since 2021, Picophotonics has been part of the EU’s REAP project (Revealing drug tolerant persister cells in cancer using contrast enhanced optical coherence and photoacoustic tomography). A major problem with current cancer treatment is that it often fails due to the development of drug resistance by a subpopulation of drug-tolerant persister (DTP) cells and the detection of DTPs poses a significant technological challenge of clinical importance. The key objective of the EU-funded REAP project is to develop a sensitive method for the specific detection of DTPs via novel lasers and detectors to enable the in vivo imaging of tumours as well as the in vitro characterisation of DTPs in cancer organoids. To this end, Picophotonics is providing high energy pulsed lasers for photoacoustic microscopy. According to Antti, participation in REAP is a very positive step for Picophotonics as the project is providing the company with an opportunity to contribute to finding new imaging methods for diagnoses of cancer and also expand its product platform. 

Manufacturing: Going to the next level will inevitably mean moving into volume manufacturing. To this end, in January 2022 the company will start to operate in a new fab set in Tampere. Successful volume manufacturing will require resolving a number of issues. The first is standard vs custom products. As Antti points out, while most of the customers want something a little different, volume manufacturing requires a set of standard parameters that involve various kinds of compromises. The challenge will be finding the right trade off so that Picophotonics can come up with a flexible manufacturing accommodating high volumes and customized products with strong differentiation against competition.

Location: Tampere the Laser Valley of Finland: In addition to Picophotonics’ proven technology, Antti sees their location in Tampere as an important factor for future success. Tampere host the R&D offices of world-renowned high-tech manufacturing brands and the region is home to several laser start-ups that are already world leaders in their sectors. As he says, Picophotonics are not the first to develop lasers in the area, and when considering future options, the company will be able to draw on a rich vein of knowledge, talent, and experience provided by the Finnish robust photonics ecosystem.

If you started again, what would you do differently?

Maybe I would finish up with my studies with a faster pace and focus purely on the business development. Even though the academic network and likeminded people can be of great help in many cases, multitasking at this scale can be very time-consuming.

When I finished my BSc, I was presented with an opportunity at Picophotonics that was too good to turn down. Since then, I’ve focussed more on finance, customer interaction and my role as CEO than on further technical studies. However, our team has excellent technology expertise that exposes me to a continuous learning process also on the technology side.

What are your words of wisdom for the next generation of entrepreneurs?

First, opportunities come from being in the right place at the right time. No matter how cliché this sound like, by exposing yourself to dynamic and innovative environments and getting to know people, new opportunities will rise. Furthermore, when you are presented with an opportunity, be brave and don’t be afraid of seizing it. If things don’t work out, learn from the experience and just be better prepared for the next one.

Second, teambuilding is crucial because when you're facing the many challenges of the entrepreneurship world, one needs to have the right people around – people with the necessary experience and knowledge who are committed to working hard for achieving success. Our team is the biggest asset Picophotonics has and we work every day to grow it stronger and larger.

Written by Jose Pozo, Chief Technology Officer at EPIC (European Photonics Industry Consortium).

Labels: Picophotonics,Antti Penttinen,q-switched,microchip,laser,SESAM,semiconductor

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