- No Piezoelectric Ringing
- High Damage Threshold
- High Extinction Ratio
- Low Insertion Loss
- Thermally Compensated
RTP (rubidium titanyl phosphate – RbTiOPO4), used in the company’s 1147 Series Pockels cells,
is a very desirable crystal material for electrooptic modulators and Q-switches. It combines
several features of KD*P and Lithium Niobate and has one major advantage over both: RTP exhibits
virtually no piezo-electric effect with electrical signals between DC and 100 kHz. There is no
ringing superimposed on the transmitted optical beam passing through the crystal. Modulators
and Q-switches made with RTP can be utilized with high power lasers operating at high repetition rates.
Freedom from piezoelectric ringing enables the use of RTP devices in high repetition rate mode
locked laser pulse extraction, laser pulse slicing, chopping and gating systems as well as in Qswitching
applications. Tests conducted at up to 100 kHz reveal no ringing in the optical waveform.
RTP has a useful optical wavelength range from 350 nm to 4300 nm. Transmittance, in the 400
to 1100 nm range, with hard, “V” type high efficiency Anti-Reflection coatings is 98.5%.
Standard AR wavelengths, at the present time, are 1064 nm and 700-900 nm. A-R coatings for other wavelengths are available.
Typical extinction ratios of RTP devices are greater than 200:1 (>20 db) measured at 633
nm. Wavefront distortion is <1/8 Wave at 633 nm. Thermal stability is excellent over a broad
temperature range. The electro-optic coefficient for RTP is temperature insensitive from about 10
0C to more than 50 0C. Because RTP crystals are not hygroscopic, in an appropriately clean, dustfree,
enclosure, all devices within the series can be used without protective windows.
The damage threshold of RTP is of the same order as deuterated KD*P, approximately 850 MW/cm2
for a 10 nanoseconds wide Q-switched pulse at 1064 nm. In gating applications with laser pulses
<100 picoseconds, the damage threshold is in the 10 GW/cm2 range.
Operating voltages for the 1147 Series are lower than those experienced for KD*P and BBO in the
same aperture sizes. A typical device (Model 1147-6-1064) with a 5.5 mm clear aperture and
AR coatings for 1064 nm has a half wave retardation voltage of 2400 Volts. Capacitance is
also low: for the Series 1147, it is about 5 picofarads. RTP has a high (>1011 Ohms)
resistivity and does not exhibit “gray track” laser damage.
The 1147 Series has an industry standard 35 mm diameter, convenient for optical mounts. The size
is compatible with the company’s Series 1059 KD*P devices and may be easily replace them in
many of the company’s E-O systems.
Series 1147 devices are being used in the FastPulse Technology’s Models 5046E, 5046SC,
and 5057 Laser Pulse Extraction / Chopping Systems, as well as the 5048, 5056, and 5060
Q-switching Systems and 8025S HV Generator.