It has been well-known that excellent optical quality BBO is one of ideal electro-optic materials for high average power application. On basis of its significant advantages over all of E-O materials in terms of temperature stability, no thermal blooming, no photo-refractive damage and high damage threshold as well as high optical quality (high extinction ratio), BBO Pockels cell has been used widely in DPL systems with high average power, high repetition and short pulse (ns) compared to A-O Q-switch.
BBO spectra range is 190-3300nm. QSB series BBO Pockels cell Q-switch transmittance is greater than 98% over 300-2000nm, The capacitance of BBO Pockels cell Q-switches is much small, about 2pF, so its switching time is much fast, about <300ps. Intrinsic extinction ratio of high quality BBO is greater than 2000:1, measured at 633nm, wavefront distortion is <λ/8 at 633nm.
Temperature stability of BBO Pockels cell is much high in comparison to KD*P and LiNbO3 Pockels cell Q-switch, accordingly, there is no thermal blooming inside it.
For BBO Pockels cell, there is almost no pizeoelectrical ringing in operation from single shot to repetition rates of more than 300KHz.
Its Quarter-wave voltage is proportional to the ratio of width between electrodes to overall crystal length, so the crystal width decrease and its length increase minish the quarter-wave voltage.
BBO crystal is slightly hygroscopic, so BBO Pockels cell is of all hermetical structure, its two ends have protective two fused-silica windows coated AR-coating.
Besides its good surface treatment (no naked-eye mechanical scratches on housing surface), the housing of QSB series BBO Pockels cell Q-switch is of oxidized aluminium, acting as heat-sink, also protecting Pockels cell Q-switch from static damage while its operation safety is considered absolutely.
Matching the housing heat-sink, its core mounting BBO crystal is ceram with properties of HV-resistance and good heat-sink.
In its assembly, no encapsulants or no cements are used, which makes it sure that there is no pollution in operation of laser system.
All in all, all designes are much scientific and industrial, no POM or PTFE (polymer plastic) is used. It is well known that the utilization of POM and PTFE which is used generally as the housing of Pockels cell Q-switch or modulators, causing a large amount of "migration" of the electrodes over a long time of use. |
