VHE Q-switch (China)

Very High Efficiency > 95%



• Unique patent-pending acousto-optic design



• Includes ‘Sure-Flow’ technology



• For linearly polarised lasers







The VHE acousto-optic Q-Switch is ideal for use in high-gain, high-power, linearly polarized Nd:YAG & Nd:YVO4 lasers. Thanks to a special design it provides up to 96% single-pass loss modulation (compared to ~85% from conventional designs).







This astonishing performance is achieved inside the industry-standard package, allowing simple integration into existing cavity configurations.







Incorporating our special ‘Sure-Flow’ corrosion resistant treatment, which allows confident, efficient water-cooling, the VHE Q-Switch can handle up to 100W of RF power.





Interaction Material

Fused Silica



Wavelength

1047 to 1064nm



Polarisation

Linear, vertical to base



Anti-Reflection Coating

< 0.2% per surface



Damage Threshold

> 1GWcm-2 (2GWcm-2 typical)



Transmission (single pass)

> 99.6%



Frequency

68MHz



VSWR

< 1.21 (50O input impedance)



Active Aperture

1.6, 2, 3, or 4mm



Rise-Time / Fall-Time

109ns/mm



Loss Modulation

> 95% (single pass)



Beam Separation

12mrad



Acceptance Angle

5mrad



RF Power Rating

100W cw



Water Flow Rate

190cc / minute, minimum



Maximum Water Temperature

+40°C (recommended, 22°C to 32°C)



Water Connectors

Screw-fit or Barbed (push-on)



Thermal Switch Cut-Off

+55°C ±5°C



Housing Material

Aluminium, with ‘Sure-Flow’ technology



Driver Model A253-yy or A253-zz





The VHE Q-Switch: Pushing the boundaries further



Q-Switching is a method frequently used to obtain short laser pulses of enhanced power. However, improvements in laser technology have lead to the situation where the maximum loss modulation provided by conventional Q-Switches is insufficient to hold off the laser output.







That was then: Alignment of two Q-Switches



For high-gain unpolarised systems, the Gooch & Housego Super Q-Switch is available but until now, there was only one way to provide the loss modulation needed to successfully Q-Switch high-gain linearly-polarised systems. This was to fit two Q-Switches in series to provide sequential depletion of the zeroth order beam. Orientation of these two devices is crucial since any raction of the first order rays back into the zeroth order will significantly reduce the loss modulation. Misalignment of the two Q-Switches could even result in a lower loss modulation than a single Q-Switch on its own.







raction is not the only drawback associated with using two Q-Switches. The relative phase of the acoustic modulation must also be considered if timing jitter is to be avoided. The increase in cavity length associated with fitting two Q-Switches will mean the pulse width will be increased. Two Q-Switches will place four optical faces into the laser cavity leading to increased insertion loss and multiple reflections. Each of the two Q-Switches must be carefully aligned at the Bragg angle while simultaneously avoiding raction losses and of course two Q-Switches will require extra plumbing for the water cooling system and RF drivers.







This is now: A Q-Switch with >95% loss modulation



Understanding the challenges laser engineers face, Gooch & Housego has developed the VHE Q-Switch. Designed for use in high-gain, high-power, linearly-polarised Nd:YAG and Nd:YVO4 lasers, the patent-pending design provides better than 95% single-pass loss modulation, compared to ~85% from conventional designs. This outstanding performance is achieved inside the industry-standard package which allows simple integration into existing cavity configurations.







The raction problem has been solved by careful alignment of the acoustics within the structure. At certain incidence angles, a laser beam will not be diffracted by an acoustic beam. These angles are built into the VHE Q-Switch