Femto Easy, ultrafast instrumentation

ROC Autocorrelator

ROC stands for Row Optical Correlator. Based on an ultra compact and robust inline setup, the ROC allows the measurement of single-shot autocorrelation traces. Specifically designed to offer the easiest user experience, they cannot be misaligned and no calibration or tweaking is needed. Also, they are easily transportable. And yes, they are rock-solid! Besides those advantages, the ROC autocorrelators provide excellent technical performances and highly accurate measurements. The ROC autocorrelators are available for different wavelength ranges and several pulse durations.

Features

  • Ultra compact
  • Installation and measurement in less than 2 minutes! No calibration necessary
  • Suitable for any repetition rate
  • Single-pulse extraction possible up to 150 kHz laser repetition rate (with Enhanced detection option)
  • User-friendly and powerful software (STAR : Software Technology for Acquisition and Retrieval)
  • Input pulse energy from few pJ to few mJ
  • Acceptable average power up to 3.5 W
  • Pulse measurement from 5 fs to 10 ps
  • Broad available spectral range

Specifications

ROC models FC FS PS1 PS3 PS5 PS10
Pulse duration range min 5 fs 20 fs 50 fs 70 fs 100 fs 300 fs
max 150 fs 500 fs 1 ps 3 ps 5 ps 10 ps
Accessible spectral range (nm) 480 - 21001 800 - 21001
Input pulse repetition rate single-shot to GHz2
Single-pulse measurement up to 150 kHz laser repetition rate (with Enhanced detection option, or 40 kHz without)
Min input pulse energy3 Single-shot 1 µJ (10 nJ with low-energy option)
1 MHz 10 nJ (500 pJ with low-energy option)
1 GHz 50 pJ (low-energy option required)
Input polarization linear horizontal or vertical
Detection CMOS 12 Bits - 3 Mpx - 72 dB
PC Interface USB 3.1 (or GigE as an option)
Beam height (mm) adjustable from 30 mm
Dimensions (mm) 55 x 56 x 265 55 x 56 x 195

1 Effective spectral bandwidth to be defined within the accessible spectral range according to customer's requirements

2 The measurements are averaged over several pulses for laser with repetition rate higher than 150 kHz. Custom versions available on request. For lower power and wider pulse duration ranges, Multi-Shot scanning versions are available (MS-ROC).

3 Those values give an order of magnitude. The exact sensitivity depends on many parameters (pulse duration, beam profile, wavelength…)

Options

Option Description
Enhanced detection Replacement of the default camera embedded in the ROC by a higher performance one to increase the specifications of the system (better temporal resolution, single-shot extraction up to 150 kHz)
Fiber input connector Plug&play collimation module with fiber connector. Can be mounted on the ROC to easily switch the input from free-space to fiber. No alignment required.
High dynamic range Software mode to increase the dynamic of the ROC signal acquisition from 12 to 16 bits. Not compatible with pure single-shot measurement as 2 images are necessary to build one autocorrelation trace
Low energy Internal or external module (depending on ROC model) to increase the sensitivity of the device when the laser power is too weak
Phase matching Default ROC configuration works for a given central wavelength. Phase matching allows tuning the SHG crystal to measure different central wavelengths with the best SNR
Small beam Internal or external module (depending on ROC model) to increase the input beam diameter when it is too small (necessary for beams typically in the range of few mm or less)
Trigger Synchronization of the ROC detection to an external signal for accurate laser single pulse extraction up to 80 kHz (150 kHz with the Enhanced detection option)

Software

The Femto Easy software has been designed to be user friendly and intuitive. This is a modern software compatible with touchscreen that can run either under Linux or Windows. It allows distant control of the devices via PC, tablet or smartphone. We can also provide custom software developments upon request.
The image is a screenshot of the ROC software interface.

Measurement of few cycle pulses

Few cycle pulse measurement example
This is an autocorrelation measurement sample of ultrashort pulse that has been performed in Politecnico di Milano with our short pulse model autocorrelator ROC FC.
On the top, the raw image of the spatially resolved autocorrelation trace.
At the bottom, the analysed autocorrelation trace integrated over the spatial coordinate. The experimental data (in red) are fitted by a Gaussian function (in blue). The full width at half maximum of the autocorrelation trace is 8.3 fs. The corresponding Gaussian pulse duration is 5.9 fs.

Measurement of low energy pulses

Low energy pulse measurement example
This measurement has been performed on a femtosecond Ti:Sapph oscillator at LCAR with a ROC FC autocorrelator.
The average power used for the measurement was with only 20 mW at 62 MHz repetition rate. It means that in this conditions 0.3 nJ per pulse was enough to get a clean measurement. At the buttom, the raw image of the spatially resolved autocorrelation trace.
On the top, the analysed autocorrelation trace integrated over the spatial coordinate. The experimental data (in blue) are fitted by a Gaussian function (in red). The full width at half maximum of the autocorrelation trace is 30.4 fs for a Gaussian pulse duration of 21.5 fs.