OPTEK developed solutions:
We have developed various devices – tunable diode lasers, avalanche photodiodes, PID lockboxes for laser stabilization, optimized Fabry-Perrot cavities, etc. Most recent developments are laser stabilization system allowing to obtain the laser linewidth of 1 Hz and Cavity Ring-Down Spectroscopy (CRDS) system operating at 266 nm wavelength for detection of acetone in human breath (ppm levels).
Some insight into scientific novelty of the work of OPTEK on Fabry-Perrot cavities can be found in recent SCI papers:
To find out more:
The stabilized laser operates at 972 nm and consists of three main parts: a light source, an external Fabry-Perrot (FP) cavity, and the PID lockbox (see Custom solution - PID lockbox). The light source, a 972 nm laser diode, is locked onto a high finesse external FP cavity using an optical and electrical feedback loop which comprises a PID lockbox set up in a Pound-Drever-Hall technique. Usually, the main reason for linewidth broadening is the mechanical noise induced in the external cavity. Our FP resonator has the finesse of over 100000 and is mechanically and thermally stabilized enabling us to reach the linewidth of 1 Hz with frequency drift below 1 Hz/s.
We also offer custom development of stabilized lasers operating at different frequencies, e.g., 972 nm, 780 nm, 370 nm and other upon request.
Cavity ring-down spectroscopy (CRDS) is an optical technique used for measuring very low absorption coefficients usually in gases. By measuring absorption coefficients of a gas at particular wavelengths it is possible to assess the gas concetrations with high precision.
OPTEK has built and delivered a CRDS system equiped with 266 nm pulsed laser for measurement of acetone concentration. During the development of the device custom optical system and software were created. The tool allows measurement of acetone concentration in real time with 1 ppm resolution.
This electronic module is intended for stabilizing external cavity diode lasers to high-finesse external resonators in the research field of optical atomic standards. The device comprises two essential blocks – a fast feedback PID lockbox, and a slow PI lockbox. The lockbox allows reaching sub-Hz laser linewidths because it is built after the same schematics as used for sub-Hz stabilized linewidth laser which is described in paper by Alnis et al. in Phys. Rev. A 77, 053809 (2008). The key specifications and images of the device as well as graphs obtained during the operation are shown below.
Fast feedback branch
- 50 Ohm inverting and non-inverting inputs. Can be used as single ended or differential;
- Input signal range ± 1V;
- Input noise of amplifier 0.92 nV/Hz^1/2, 2.3 pA/Hz^1/2;
- 10 MHz proportional bandwidth (-3dB);
- Proportional gain switchable -30…+20 dB in 10 dB steps and using fine adjustment;
- Input to output delay time 13 ns.
Slow feedback branch
- Input impedance 10 kOhm;
- Input amplifier noise 3 nV/Hz^1/2;
- Low input offset drift 0.2 μV/degC;
- Proportional bandwidth 70 kHz(-3dB);
- Integrator low frequency voltage gain 70 dB;
- Output range ± 12 V. Output current ca 10 mA;
For non-contact thickness measurements of thin layers and films Optek has developed a special software - MThickness. The software comprises interference fringe separation technique in which the interference fringes of the reflected or transmitted spectra are analyzed for thickness measurement. The software can be used with any OceanOptics spectrometer if OmniDriver is installed. The OmniDriver is a free software package available at OceanOptics. The software can also be used for processing any saved spectra using user defined recipes. The software and the necessary hardware can be obtained from Optek. Please, contact us at info[at]optek.lv for more information.