Support

FAQs - Femtosecond

The operating environmental temperature (air temperature) should be in the range of 16°C-26°C, the operating laser head temperature range is 20°C-24°C. The coolant temperature needs to be set to the final chiller setting given in the certificate of conformity (typically a value close to 22°C).

Related to: taccor / gecco / venteon

Please use an appropriate coolant preventing aluminum corrosion. 

Recommended coolants are Glysantine G48 or LIQ-705CL-B (Koolance) in a 1:2 mixture with distilled water. Set coolant temperature to the final chiller setting given in the certificate of conformity (typically a value close to 22°C). 

Related to: taccor / gecco / venteon

If the laser is operated with a third party chiller, it must be ensured that the flow does not exceed 2 l/min and the pressure does not exceed 1 bar. Too high flow values can cause turbulent flow in the housing causing excessive noise on the output. Too high pressure can cause serious system damage.

Related to: taccor / gecco / venteon

The power supply unit will automatically switch the laser off if the in-built over temperature protection system is activated. The laser can only be switched back on when the laser head has cooled.

In case of overheating please check that adequate heat sinking is provided to the laser head.
Please ensure that the chiller is connected to the laser head and the fluid is circulating properly, which can be verified by opening the chiller and checking for movement of the water. The chiller temperature should be set to the value given in the certificate of conformity (typically a value close to 22°C).

Please ensure that nothing is blocking the fans of the power supply unit and check if all the fans are rotating properly.

Related to: taccor / gecco / venteon

For measuring the output power please use a power meter that is usable at the specified power of your laser.  Ensure that the wavelength is set according to the value specified in the certificate of conformity and place the power meter in front of the output aperture. Please perform the measurement without any additional optics between the output aperture of the laser head and the power meter.

Related to: taccor / gecco / venteon

There are different causes which can lead to a performance change of the laser system. Please check the following steps to ensure the performance change is not caused by an external factor. For gecco and venteon systems please ensure to check steps 1 – 7 prior to any cleaning or realignment. For venteon systems also include step 8 and 9.’ 

  1. Please ensure that you measured the output power without any external optics between the output aperture and the power meter and that the power meter is set to the correct values.
  2. Please switch the system off completely (including power supply unit), wait for approximately 30min and restart the system.
  3. Please ensure that the cooling system is running properly:
    1. Are the tubes connected?
    2. Is the chiller switched on?
    3. Is the fluid running?
    4. What are the temperatures of the laser head and power supply unit and are the temperatures settling?
  4. Please ensure that all cables are secured properly at the laser head and at the power supply unit.
  5. Please check if there is any damage or kink visible on the fibre.
  6. Please ensure that the fibre is not tied to any water hoses as the vibrations of the circulating fluid can lead to a performance change of the system.
  7. Please ensure that the laser head is mounted on a flat and clean metallic surface with no more than a torque of 2Nm.
    If the base, where the laser head is mounted on, is slightly bent, if there is some debris between the laser head and the base or if the laser head is mounted with more than Nm, screwing down can lead to a bending of the laser housing, which affects performance.
    Please make sure that both sides (bottom face of the laser and the table) are clean. Unscrew the laser and check the output power again. The laser head can be screwed down gently while observing the output power. The power should not change by more than 2%.
  8. For venteon lasers please ensure a proper coupling to the spectrometer. If using a wedged substrate to pick the beam, be sure to use the front reflex to avoid spatial effects. USB spectrometers need to be calibrated with respect to the Si-based detector sensitivity.  
  9. For venteon systems please move the motorized dispersion wedge to optimize the spectrum, if possible.
  10. For gecco and venteon systems please clean optics according to the manual if previous steps did not solve the problem.
  11. For gecco and venteon systems please realign the cavity according to the manual if previous steps did not solve problem.
  12. If the problem still occurs please contact our Laser Quantum Support Team.

For all service and support enquiries please contact Laser Quantum on:

 t: +44 161 9755300 (UK)       t: +1 408 5100079 (USA)       t: +49 7531 368371 (GERMANY)

support@laserquantum.com

Related to: taccor / gecco / venteon

There are different causes which can prevent the system from lasing or modelocking. Please check the following steps to ensure this is not caused by an external factor. For gecco systems please ensure to check steps 1 – 6 prior to any cleaning or realignment. For venteon systems also include step 7.

  1. Please switch the system off completely (including power supply unit), wait for approximately 30min and restart the system.
  2. Please ensure that the cooling system is running properly:
    a. Are the tubes connected?
    b. Is the chiller switched on?
    c. Is the fluid circulating?
    d. What are the temperatures of the laser head and power supply unit and are the temperatures settling?)
  3. Please ensure that all cables and the interlock connector are secured properly at the laser head and/or at the power supply unit.
  4. Please ensure that the key is turned to the 'on' position, the 'Laser' button is pressed and that the warm up phase is finished.
  5. Please check if there is any damage or kink visible on the fibre.
  6. Please ensure that the laser head is mounted on a flat and clean metallic surface with no more than a torque of 2Nm.
    If the base, where the laser head is mounted on, is slightly bent, if there is some debris between the laser head and the base or if the laser head is mounted with more than 2Nm, the screwing down can lead to a bending of the laser housing, which affects performance.
    Please make sure that both the bottom face of the laser and the table are clean and screw it gently down while observing the output power. The power should not change by more than 2%.
  7. For venteon systems please move the motorized dispersion wedge in the counter clockwise (-) direction and try to start modelocking.
  8. For gecco and venteon systems please clean optics according to the manual if previous steps did not solve problem.
  9. For gecco and venteon systems please realign the cavity according to the manual if previous steps did not solve problem.
  10. If the problem still occurs please contact our Laser Quantum Support Team.

Realted to: taccor / gecco / venteon

When the laser receives a back reflection from the setup (e.g. when coupling the laser output to a fibre) it is possible that the shutter closes automatically during operation. Therefore please avoid feeding back reflected light from optical components such as a fibre facet, which can be achieved by introducing a slight angle between the incoming beam and the component’s normal. Thus the reflected beam does not travel back the same way as the incoming beam. The coupling efficiency to a fibre should not be affected significantly by a small angle, FC/APC fibres are recommended.

If back-reflections into the laser can be excluded and the shutter still closes automatically, please contact the Laser Quantum Support Team.

For all service and support enquiries please contact Laser Quantum on:

 t: +44 161 9755300 (UK)       t: +1 408 5100079 (USA)       t: +49 7531 368371 (GERMANY)

support@laserquantum.com

Related to: taccor / gecco / venteon

In case your system has a change in performance please contact our Laser Quantum Support Team.

We can connect to all our ultrafast laser systems with a ULC power supply unit remotely. A remote session will take place at an agreed date and time and in order for us to be able to remote connect to your ultrafast laser system you will need to download our RemoteCom for Ultrafast software from our website: http://www.laserquantum.com/products/detail.cfm?id=60

For the remote session the laser needs to be enabled and connected to a computer with the RemoteCom for Ultrafast software running. A stable internet connection is required and the firewall needs to allow sending/receiving data from our server.

Laser Quantum will provide you with more detailed information on how to set up your system prior to the remote session.

Related to: taccor / gecco / venteon

In case the laser system needs to be send in for service Laser Quantum will provide you with a Return Material Authorisation (RMA) Form and instruction on how to package and return the laser safely to us for assessment. The laser has to be shipped in the original packaging.

Please do not return the laser without prior contact with and agreement from the Laser Quantum Support Team.

For all service and support enquiries please contact Laser Quantum on:

 t: +44 161 9755300 (UK)       t: +1 408 5100079 (USA)       t: +49 7531 368371 (GERMANY)

support@laserquantum.com

Related to: taccor / gecco / venteon

To prevent the laser from serious damage it is important that the laser is shipped in the original packaging. If you don't have the original packaging anymore please contact our Laser Quantum Support Team. We will provide you with information on a new packaging and packaging instructions.

For all service and support enquiries please contact Laser Quantum on:

 t: +44 161 9755300 (UK)       t: +1 408 5100079 (USA)       t: +49 7531 368371 (GERMANY)

support@laserquantum.com

Related to: taccor / gecco / venteon

There are cases where the optics of a gecco or venteon need to be cleaned. This is only necessary if the gecco or venteon

  1. does not self start modelocking
  2. has low output power
  3. shows deviation to the spectrum shown in the certificate of conformity (e.g spectrum narrowing or broadening, cw breakthrough)
  4. shows Q-switching

In such case please ensure to check the steps described in FAQ 'How do I measure the output power correctly?' and FAQ 'The output power and/or the spectrum do not match the data specified in the certificate of conformity - what can I do?' prior to any cleaning!

Related to: gecco / venteon

Cleanliness of the Ti:sapphire crystal, the mirrors and the windows within the gecco or venteon is of general importance for proper operation. For cleaning of the gecco or venteon optics please ensure to wear clean disposable gloves to avoid contamination. Remove the access panel, check for signs of contamination on the optics and disable the laser. Do not clean the optics whilst the pump laser is enabled! All optics within the gecco or venteon are cleaned with optics grade acetone and lens cleaning tissue.

For more detailed information on how to clean the optics please refer to the user manual.

Related to: gecco / venteon

Generally the gecco or venteon cavity should not be re-aligned. Only in the highly unlikely event that the performance changes described in FAQ 'When do the optics in a gecco or venteon need to be cleaned?' are not solved by repeatedly cleaning the optics or re-adjusting the pump power it is recommended to re-align the cavity.

For realignment, after referring to the user manual, please ensure to wear clean disposable gloves to avoid contamination and switch the gecco or venteon to maintenance mode via the user screen. Only use the two adjustable end mirrors of the cavity, M9 & M6 (OC) for the gecco and M8 & M6 (OC) for the venteon. Please read the user manual carefully prior to any realignment.

If the attempt to re-align the laser fails to bring the laser back in spec please contact the Laser Quantum Support team.

For all service and support enquiries please contact Laser Quantum on:

 t: +44 161 9755300 (UK)       t: +1 408 5100079 (USA)       t: +49 7531 368371 (GERMANY)

support@laserquantum.com

Related to: gecco / venteon

Yes, each of our taccor, gecco and venteon systems can be purchased with the repetition rate control option. Control of the repetition rate and active feedback is enabled by cavity mirrors mounted on a fast and slow piezo crystal enabling rapid feedback and drift control simultaneously. In combination with the TL-1000 repetition rate stabilisation unit, timing jitter below 100fs can be achieved.

Alternatively, the repetition rate can be slightly changed by variations of the temperature of the cooling system. The change of the repetition rate is depending on the coefficient of thermal expansion of aluminium. Increasing the temperature leads to a smaller repetition rate, decreasing the temperature leads to a bigger repetition rate. In a taccor system for example, a temperature change of 1°C leads to a change in repetition rate of approx. 27kHz.

Related to: taccor / gecco / venteon

Yes, some care has to be taken so that the supported bandwidth of the steering mirrors is larger than the spectral width of the oscillator. Typically, coated silver mirrors should be used as standard dielectric mirrors may not be broadband enough.

See HERE for information on the venteon range of silver mirrors.

Also, (dielectric) multistack mirrors may spoil the phase of the pulse, as they may introduce phase jumps in the spectral regions where the stacks join, which will destroy the compressibility of the pulse, i.e. the short pulse duration.

Related to: venteon

Measuring broad spectra as they are emitted by the venteon oscillator series requires an intensity calibrated spectrometer. The typical compact CCD spectrometer is not intensity calibrated, meaning that portions of spectrum are displayed differently from a measurement using a calibrated instrument. This is especially true for the long wavelength edge above 1000nm, which will be largely underestimated by non-calibrated spectrometers.

High accuracy intensity calibrated spectrometers include; the Ando AQ6317B, or the Yokogawa AQ6370.

Related to: venteon

The ultrashort pulses are made up of a coherent superposition of many different wavelengths, this is especially true for few-cycle pulses. When propagating through material, the wavelength dependent refractive index results in different propagation speeds for the different individual wavelengths (dispersion), which in turn results in a temporal broadening of the pulse (chirping of the pulse due to group velocity dispersion). To be able to measure the duration of few-cycle pulses, all dispersion in the beam path has to be compensated for, this is also true for the optics inside the measuring instrument. At these large bandwidths, the effect of the dispersion by propagating through a piece of 1mm fused silica is not negligible. As an example, the dispersion of the beam splitter of a typical autocorrelator has to be compensated for to be able to measure 5fs pulses.

HERE for more information on the venteon range , or HERE for information on the Laser Quantum pre-chirper.

Please click HEREfor information on the venteon range of of DCM mirrors.

Related to: gecco / venteon / taccor

For a near transform limited 5fs pulse as from the venteon ultra propagating through 10mm of BK7 glass, the pulse would be already stretched to 360fs. Propagation through 1mm of fused silica would stretch the same pulse to approx. 20fs, the same as travelling through 2m of air at room temperature. As an example, to compensate for passing through 15mm of fused silica (which adds about 540fs² of GVD) four bounces, off a pair of DCM11 mirrors, are needed (one pair of DCM11 mirrors introduces approx. -130fs² of GVD, i.e. approx. -65fs² per mirror)

Please click HERE for more information on the venteon range of DCM mirrors.

Please click HEREfor information on the venteon range of of DCM mirrors.

Related to: gecco / venteon / taccor

For extremely short pulses, such as few-cycle pulses, this can best be done with a combination of Dispersion Compensating Mirrors (DCMs) and wedges. DCMs compensate the dispersion in discrete steps, and adding a pair of wedges enables continuous adjustment of the compensation to reach the optimal amount needed to gain the shortest pulse duration at the target. Alternatively, these can be combined together in a “pre-chirper” with motorized control to make regular alterations easier.

Please click HEREfor information on the venteon range of of DCM mirrors or HERE for wedges.

Related to: gecco / venteon / taccor

Ultrafast systems are used for applications that vary from customer to customer, so the final negative dispersion compensation needed for each set up, and possibly for each experiment, is different. It is Laser Quantum’s view that the negative compensation needed for the final interaction in the end users experiment is what matters and the compensation should be done only once, as this gives the user the best possible result.

Please click HEREfor information on the venteon range of of DCM mirrors or HERE for wedges.

Related to: gecco / venteon / taccor

To obtain the pulse duration measured during manufacture, the complete spectrum is needed. Also the outer low level wings do contribute considerably to getting the short pulse duration as specified. Thus, clipping the edges of the spectrum or using dispersive mirrors outside their specified range for the dispersive properties will result in degradation, and the pulse duration not being able to reach the value specified.

Please click HEREfor information on the venteon range of of DCM mirrors.

Related to: venteon

The venteon SPIDER is designed for input of an s-polarized beam, matching the s-polarized output from a venteon OPCPA. Other pulse diagnostic devices, such as e.g. autocorrelators, are typically designed for p-polarized input, matching the p-polarized output from the venteon as well as the taccor series of oscillators.  

Please click HEREfor information on the venteon range of opto-mechanics designed for few-cycle pulses.

There are different approaches to use; one would be to use a wave plate. However, the bandwidth of wave plates may be limited, and not rotate all wavelength components by the same amount. Also, the wave plate will introduce dispersion. A much more suitable option for use with extremely short and few-cycle pulses is the use of a polarization turning periscope, which is made from reflective optics suitable for handling the bandwidth whilst introducing only negligible dispersion.

Please click HEREfor information on the venteon range of opto-mechanics designed for few-cycle pulses.

Related to: gecco / venteon / taccor

The wedge inside the oscillator is not only used for coarse adjustment of the carrier envelope phase in CEP stabilized systems (the fine adjustment and stabilization is done via modulation of the pump power), but also for the fine tuning of the dispersion of the resonator. To obtain the extreme spectral bandwidth, in the range of a few hundred nm of the venteon series of oscillators, the overall dispersion of the resonator, while in mode-locked operation, has to be as close as possible to zero.

Therefore, the wedge position inside the resonator matters considerably for obtaining the broadest spectrum for the short pulse measured during production. Please keep in mind that the wedge position might be changed after installation since the ambient conditions are different from the place of production.

Related to: venteon

The venteon interferometers do not use small apertures in their setup, so beam pointing that would translate to a fluctuating power level of the CEP beat signal is not critical for the venteon CEP5 approach and does not need any stricter requirements compared to other techniques. Also, the signal power is not sensitive to temperature drifts or misalignment. In terms of stability, the CEP stabilized laser system (the pump laser and femtosecond oscillator) and f-to-2f interferometer are each built on an all-water-cooled monolithic breadboard, so thermal drifts are minimised as much as possible for those systems.

Related to: venteon

The venteon CEP5 approach does not require a PCF fibre for spectral broadening, the octave-spanning spectrum is obtained directly from the laser. There is no nonlinearity involved other than a simple SHG of the IR part of the spectrum in the f-to-2f interferometer!

Related to: venteon

Some applications require a spectrum with less bandwidth and smoother shape than offered by an octave spanning spectrum but still need CEP stabilization. To fulfil these requirements, the venteon power uses the more traditional approach - using a PCF fibre for spectral broadening, keeping a high power output from the oscillator with a smooth shape, less than octave spanning spectrum, for use in these experiments.

Related to: venteon

Not at all! The venteon f-to-2f interferometer is very compact, almost common path configuration and hands-off, so you don't have to touch it after installation.  Should the beam in front of the interferometer be misaligned for some reason, there are three pinholes included in the setup and a readjustment can be performed by doing a beam-walk on these irises to obtain a good beat signal. This re-adjustment is very straight forward, since there are only two mirrors to align.

Related to: venteon

This approach still requires a nonlinear broadening, which can cause amplitude-to-phase noise conversion affecting the stabilization effort. Since the venteon spectra are broad enough, we don't need this technique and also require no fibres! (Except in the venteon power) The main advantage of the venteon CEP5 f-to-2f interferometer is that it needs only the wings of the spectrum as input and thus works with less than 20 mW of input average power, a really efficient approach! For the DFG approach > 15 0mW of power has to be used for the stabilization. Additionally, the venteon systems deliver much shorter pulses, so any CEP effect is much more pronounced!

Related to: venteon

The venteon CEP5 f-to-2f interferometer setup is almost common path. A common path interferometer is typically used with amplified pulses, where due to the available pulse energy a lower efficiency all-in-line setup can be used. With typical pulse energies from an oscillator however, the almost common path version is the most stable and efficient solution. Dividing and recombining the IR part only in the interferometer makes no major stability difference here as it is only a short path length built on a monolithic base. Choosing this way, makes the interferometer insensitive to dispersion of the in-line part of the setup, since the delay between both arms can be controlled easily. The frequency doubling and beat signal generation are all done in-line for best long term stability.

Related to: venteon

A SNR of >30 dB (@ 100 kHz detection bandwidth) for the beat signal is the standard specification of our systems, as well as typically that by other manufacturers. The venteon octave spanning oscillator typically delivers >40 dB SNR for the beat node from the interferometer (@ 100 kHz detection bandwidth) - venteon works in close collaboration with Menlo Systems for the CEP stabilisation and their locking electronic works very well with the power levels and SNR provided by the venteon interferometer.

Related to: venteon

The mirrors are designed for 6° angle of incidence, but everything between 0 and 10° is no problem, if you go beyond 15 ° the coating properties are slightly shifted and oscillations get out of phase.

The standard pre-amp system is limited by the nonlinearities in the fiber amplifier, hence a 1nJ output energy. We can, however, customise a system that reduces the peak power by stretching the pulse prior to the input, followed, if required by post-amplification compression. In this way, we can boost the output of the 1µm narrow bandwidth beam up to ~100nJ at reduced repetition rate of 1 MHz.

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