A femtosecond (fs) mid-infrared (MIR) optical parametric amplifier (OPA) for microscopy

ANU researchers have developed the MIROPA-fs-M, a femtosecond mid-infrared optical parametric amplifier primarily aimed at the nonlinear microscopy market, especially in the areas of 2- and 3-photon imaging.

Background

Nonlinear microscopy is a standard tool used by a range of medical scientists. Many neuroscientists currently work with 2-photon excitation, and have just recently started exploring the realm of 3-photon excitation.3-photon excitation ensures a better confinement of the excitation than 2-photon excitation when focussing deep inside scattering media, this wavelength window provides optimal penetration in biological tissues owing to reduced absorption of water, and matches the 3-photon excitation spectra of red fluorochromes commonly used in biology. 3-photon excitation can also be employed to extend the region of useful imaging in to the deep UV. Due to these various advantages the 3-photon excitation/microscopy market, whilst relatively new, is a rapidly growing market segment.

The MIROPA-fs-M is a femtosecond mid-infrared optical parametric amplifier primarily aimed at the nonlinear microscopy market. It offers a unique architecture that significantly reduces downtime in comparison to traditional optical parametric oscillator (OPO) systems used as light sources for various purposes, at a lower cost base.

Technology

The MIROPA-fs-M is a two-stage OPA (optical parametric amplifier) based on fan gratings in MgO:PPLN. The first preamplifier stage uses a long PPLN crystal and the second stage a shorter crystal. The grating period spans over a specified distance. Crystal surfaces are coated at the pump, signal and idler wavelengths, although the idler coating is not optimised since for the envisaged application only the signal output is required. Operated around 60C, this range of grating periods allows signal wavelength between 1315nm and 1750nm to be generated from a 1035nm pump-laser. This wavelength band is required for 3-photon imaging in nonlinear microscopy. Additionally, a third MgO:PPLN crystal is included in the package to create a second harmonic generator (SHG). The grating periods of this crystal allows SHG of the signal to generate wavelengths between ~745 nm and 875 nm. This wavelength band is used for 2-photon imaging.

Benefits of the MIROPA-fs-M include:

  • Small footprint; compact
  • Computer controlled; hands-free operation; turn key
  • Robust long-term operation
  • High beam quality
  • Cost effective
  • Air cooled
  • High conversion efficiency
  • Broad tuning range

Further information about the MIROPA-fs-M, including technical specifications for the unit and technical requirements for pump-lasers, can be found at hotlightsystems.com.

Opportunity

The MIROPA-fs-M requires pairing with an appropriate high-powered pump-laser. ANU is seeking engagement with laser manufacturers (with suitable high-powered pump-lasers) who are interested in establishing either (i) product evaluation for OEM integration or (ii) non-commercial evaluation of MIROPA-fs-M (with their laser product) for the purposes of exploring mutual opportunities to commercialise the OPA. ANU is also interested in general feedback regarding our technology, and would welcome input from laser manufacturers with similar OPA products on the market.

Potential applications/markets for the MIROPA-fs-M include:

  • Multiphoton microscopy
  • Deep tissue penetration and 3-photon brain imaging
  • Non-linear imaging applications
  • 2-photon polymerization
  • Spectroscopy applications
  • Microsurgery
  • Microdissection
  • Mid-infrared OCT

IP status

National Phase patent filing ongoing. ANU is seeking protection in AU, CAN, CN, EU, JP and the US; no National Phase filings have yet been granted. For more patent information please see: US2017/0199444 A1.