Labs & Equipment

Time resolved optically pumped scanning optical microscope (TROPSOM)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pump-probe setup with subpicosecond temporal and submicron spatial resolutions for direct spin-waves mapping. Key elements of TROPSOM setup are:

Femtosecond Laser System with tunable wavelength

TEMA + TOPOL (OPO) laser system (Avesta Project LTD)

Pulse duration <120 fs

Three outputs: 730-1080, 1050, 525 nm

Pulse repetition rate 70 MHz

Average power up to 800 mW

High-clearence micro-objectivies
Olympus and Mitutoyo

Magnification x20 and x50, NA 0.4 and 0.42 allow to get spot diameters ~1.5 μm. Working distancies 12 and 17 mm 

Three-coordinate piezo-translator
Piezosystem Jena

The translator is used to shift pump and probe spots on the sample. Motion within a range of 0-80 μm with resolution down to 10 nm.

Water-cooled electromagnet

The magnet is specially designed by AMT&C Group to provide fields up to 2 T with poles distance up to 40 mm.

Time-resolution and Detection system

The probe beam polarization is analyzed by an optical bridge detector composed of a Wollaston prism and balanced detector. Lock-in amplifier locked to the pump modulation frequency of 1 MHz. Pump is modulated by the acousto-optical modulator (Avesta Project Ltd.). The temporal resolution is obtained by using a 600mm-long retroreflector mounted on a linear translation stage (Thorlabs): time window 4 ns, temporal resolution down to 10 fs.

 

Recent publications

N.E. Khokhlov, et al., Optical Excitation of Propagating Magnetostatic Waves in an Epitaxial Galfenol Film by Ultrafast Magnetic Anisotropy Change, Phys. Rev. Applied 12, 044044 (2019).

 

Time resolved magneto-optical spectroscopy 

Pump-probe spectroscopic setup with subpicosecond-time and down-to-micron spatial resolution consists of several important parts:

Laser system
Regenerative Amplifier PHAROS + Optical Parametric Amplifier ORPHEUS (RA + OPA)

PHAROS SP-06-200-PP (Light Conversion)

Output pulse duration 190 fs

Output average power 5 W

Central wavelength 1028 nm ± 5 nm

Pulse repetition rate 1 kHz – 1MHz

Max. pulse energy 1mJ

Oscillator output is optional

ORPHEUS PO15F1H (Light Conversion)

Tuning range 630 – 1030 nm (Signal), 1030 – 2600 nm (Idler)

Output pulse duration 120 – 190 fs

Average power 500 mW

Pulse repetition rate 5 kHz

Laser system enables two-color pump-probe experiment.

High-clearance reflective microobjective Newport

Magnification x15, NA 0.4 allows to get spot diameters ~5 μm. Working distance 13 mm. No dispersion in wavelength range 200-20000 nm.

Electromagnets

Various electromagnets provide tunable DC magnetic fields up to 1 T. Configuration of magnets allow measurements in Faraday and Voigt geometries, and in a geometry of a longitudinal magneto-optical Kerr effect.  

Time-resolution and Detection system

The probe polarization change is measured by the detection scheme including optical balanced detector and Wollaston prism. Lock-in amplifier reference channel is on the pump modulation frequency up to 2 kHz; Pump is modulated by the optomechanic modulators. The temporal resolution is provided by a linear translation stages (Newport and Thorlabs) 600 and 300 mm-long (time window 4 and 2 ns, resolution down to 10 fs).

 Cryostat 

Continious flow optical cryostat Microstate HE (Oxford Instruments) enables pump-probe experiments at temperatures down to 10 K. Cryostat can be used in combination with electomagnets and with microobjective.

 

 

 

Recent publications

I. O. Karpovsky, et al., Laser-induced magnetization precession in the magnetite Fe3O4 in the vicinity of a spin-reorientation transitionJ. Phys.: Conf. Ser. 1400, 077001 (2019).

L. A. Shelukhin, et al., Ultrafast laser-induced changes of the magnetic anisotropy in a low-symmetry iron garnet film, Physical Review B 97, 014422 (2018).

 

Picosecond acoustics

Picosecond acoustics setup is a special part of the time resolved magneto-optical spectroscopy. Specially designed pump and probe beam pathes enable studies of the dynamics of optical and magneto-optical effects in the samples subjected to picosecond-long strain pulses.

Recent publications

Ia. A. Mogunov, et al., Ultrafast Insulator-Metal Transition in VO2 Nanostructures Assisted by Picosecond Strain Pulses, Physical Review Applied 11, 014054 (2019).

 

Dielectric spectroscopy

 

Recent publications

R. M. Dubrovin, et al., Unveiling hidden structural instabilities and magnetodielectric effect in manganese fluoroperovskites AMnF3Phys. Rev. B 98, 060403(R) (2018).

 

Optical spectroscopy

 

 

Scanning-probe and optical microscopy

 

 

Time-domain THz spectroscopy and THz pump/optical probe setups

THz-TDS setup and THz pump/optical probe setups will be constracted durining 2020 based on the 35-fs regenerative amplifier REUS (Avesta Project Ltd). The equipnent is being purchaced under the support from the Russian National Initiative "Science".

 

Whiteboard & coffee-machine

Scientific discussions are more productive with fresh coffee in a cup and a marker in a hand.

 


 

Equipment we tested in FerroLab

 

Optomechanics ST1 ENGINEERING KOREA

 

Today we got into the hands of the optomechanics of fabrication of the St1 Engineering, Korea. The trial set courtesy of our partners, In-Science company. A few different products are in the set:

  • X- and z-translation stages
  • Post holder
  • Tilt platform
  • Optics holder

All items are made of anodized aluminum, but x-stage is made of steel.

Post holder is 1/2 inch. size and is well match the Thorlabs post. It has spring-loaded thumbscrew, like Thorlabs. It is more convenient than simple thumbscrew. But manufactures did not make the hex hollow for locking. There is some sticker on this place, but there is no wonted hollow under that. The thumbscrew is sitting nice in the thread. Standard M6 tapped hole on bottom.

Optics holder is assembled from well-matched details, no noticeable slackness. The fine clamp is very smooth to the touch. There is M6 tapped hole on bottom.

Linear stages are smooth in movement. They are fully lockable. The z-stage has side lead screw. That may be more convenient than Standa solution at vertical stages. The stages could be attached to each other directly, but not to the optical table –some base is needed. Vertical stage has M6 and M3 holes, x-stage – M3 holes only. This solution is not convenient as M6 and M4 are used usually. Standa has the same issue.

Tilt platform could be mounted in horizontal or vertical positions both with M4 holes. The adjustment knobs are made of plastic suddenly, not of aluminum. The solution is looking untrustworthy, fragile. And with stickers again. Four M4 holes on the surface are convenient and give the freedom to install some elements like prisms.

 

In conclusion, the quality of the items is at the level of Thorlabs and Standa companies, some aspects are more convenient, but some (stickers, plastic parts) are unconventional and may be the issues of the products. Generally, the products may be used with optomechanics of famous brands (Thorlabs, Standa, others) together as they are compatible and with the nice quality.