Growth and Properties of RTP Crystals with High Resistivity

doi:10.16553/j.cnki.issn1000-985x.2025.0135

Abstract

Abstract: RTP crystals with large size and high resistivity were successfully grown by the top-seeded solvent growth method combined with dynamic temperature field control technology， and their properties were researched. The crystal size reaches 54 mm ×68 mm×52 mm and its weight reaches 265 g. The internal quality is uniform and the crystallization is intact. The resistivity of the crystal is concentrated within the range of 1.0×10¹²~1.4×10¹² Ω·cm. The absorption of gray-tracking resistance is 125 ppm/cm after co-irradiation at the same crystal spot for 1 000 s by 1 064 and 532 nm laser. The electron probe micro-area composition analysis test result indicates that the molar percentage of each atom is closer to the stoichiometric ratio in the RTP crystal with higher resistivity. The RTP crystal with resistivity of 1.6×10¹² Ω∙cm is no current leakage or breakdown when it is pressurized with a DC voltage of 3 200 V for 1 200 h. Within the temperature range from -40 ℃ to 70 ℃， the RTP electro-optic Q-switch could operate normally and the extinction ratio is higher than 20 dB@1 064 nm. The laser induced damage threshold of the RTP crystal is 1.78 GW/cm²@1 064 nm & 9.6 ns. These results provide important basis for the application of RTP crystals as a key material for electro-optic Q-switch.

Key words: RTP crystal; resistivity; absorption of gray-tracking resistance; RTP electro-optic Q-switch; extinction ratio; laser induced damage threshold

CLC Number:

O782

WANG Shiwu, WANG Hongyan, WANG Hui, NIE Yi, ZHANG Fang, ZHU Haiyong, MA Aizhen, GAO Jia, KUANG Yongfei, ZHANG Xingyu. Growth and Properties of RTP Crystals with High Resistivity[J]. Journal of Synthetic Crystals, 2025, 54(11): 1899-1906.

Figures/Tables 10

Fig.1 Photograph of RTP crystal boule

Fig.2 Powder XRD patterns of RTP crystal

Fig.3 Absorption coefficient curve of RTP crystal exposed to 1 064 nm laser and 532 nm laser

Fig.4 Resistivity distribution of RTP crystal

Fig.5 RTP crystal resistivity at different electric field intensity

Table 1 EPMA result of samples with different resistivity

Element	Molar percentage/% （Sample 1：2.1×10¹⁰ Ω·cm）	Molar percentage /% （Sample 2：3.6×10¹² Ω·cm）
O	74.951	60.982
P	9.964	14.108
Ti	5.375	11.695
Rb	9.711	13.215

Table 2 Withstand voltage time of RTP electro-optic Q-switches with different resistivities

Q-switch	Resistivity at 25 ℃/（Ω·cm）	Withstand voltage time/h	Phenomenon
Q-switch 1	4.4×10¹⁰	43	Black
Q-switch 2	1.9×10¹¹	140	Black
Q-switch 3	1.6×10¹²	1 200	Not black

Fig.6 RTP electro-optic device of Crystech for commercial use

Table 3 Extinction ratio of RTP electro-optic Q-switches at different temperatures

Q-Switch	Temperature/℃	Static extinction ratio/dB	Dynamic extinction ratio/dB
Q-Switch 4	-40	31	30
	25	36	34
	70	33	31
Q-Switch 5	-40	26	24
	25	33	31
	70	31	30
Q-Switch 6	-40	28	26
	25	35	32
	70	32	31

Fig.7 Relationship between energy density and laser damage probability of RTP crystal

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