Open Access
Add to BibSonomy
Abstract
The laser diode (LD)-pumped efficient high-power cascade Tm:GdVO4 laser simultaneously operating on the 3F4 → 3H6 (at ∼2 μm) and 3H4 → 3H5 (at ∼2.3 μm) Tm3+ transition was first reported in this paper. The cascade Tm:GdVO4 laser generated a maximum total continuous-wave (CW) laser output power of 8.42 W with a slope efficiency of 40%, out of which the maximum ∼2.3 μm CW laser output power was 2.88 W with a slope efficiency of 14%. To our knowledge, 2.88 W is the highest CW laser output power amongst the LD-CW-pumped ∼2.3 μm Tm3+-doped lasers reported so far.
© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
1. Introduction
The mid-infrared ∼2.3 μm is the seat of strong absorption lines of such atmospheric pollutants as HF, CO, CH4, and H2CO and blood glucose, which has important applications in atmospheric environment monitoring [1] and non-invasive blood glucose measurement [2–4]. In addition, the ∼2.3 μm lasers can also be used as the pump source for mid-infrared optical parametric oscillators [5] and the drive source for the generation of high-order harmonics [6]. Using 3H4 → 3H5 Tm3+ transition is a simple and cost-efficient method to obtain ∼2.3 μm laser, as shown in Fig. 1(a).
Fig. 1. (a) Partial energy level scheme of Tm3+ in GdVO4: red and pink arrows, pump and laser transitions, respectively; green arrows, non-radiative (NR) relaxation; blue arrows, cross-relaxation (CR) and energy-transfer upconversion (ETU) processes. (b) Cascade lasing.
It has been shown that vanadate crystals such as YVO4, LuVO4, and GdVO4 are very promising laser host materials for doping with rare-earth ions (RE3+) [7]. Especially for GdVO4 crystals grown by the Czochralski method, due to the higher thermal conductivity (10.1 W/(m·K) for a-axis [7]) and the lower thermal expansion coefficient (1.14 × 10−6 K-1 for a-axis [8]), they are more suitable as the host materials of the lasers operating at high power. The GdVO4 crystals are tetragonal (sp. gr. I41/amd) and optically uniaxial (positive). The relatively low thermal expansion coefficient and the positive thermo-optic coefficients [9] result in the weak positive thermal lens, which is essential for microchip laser operation [10]. Furthermore, the natural birefringence property of the GdVO4 crystals dominates the thermally induced birefringence effects, which avoids undesirable thermal effects on laser performance and improves beam quality [11]. When the GdVO4 crystals are used as the host materials for trivalent thulium ions (Tm3+), the maximum absorption cross-section of the Tm:GdVO4 crystals (6 at.%) reach 4.0 × 10−20 cm2 at 799.1 nm (E||c), and the absorption band exceeds 10 nm extending beyond 810 nm [7].
To date, the efficient high-power 3F4 → 3H6 Tm3+ transition at ∼2 µm has been extensively studied and realized by employing a variety of Tm3+-doped laser crystal, e. g. Tm3+-doped fluoride [12] and oxide [13] laser crystal. However, limited by the large quantum defect, the severe thermal effect, and the easily quenched 3H4 state lifetime by both non-radiative (NR) multi-phonon relaxation and cross-relaxation (CR), realizing the efficient high-power ∼2.3 μm continuous-wave (CW) laser operation based on the 3H4 → 3H5 Tm3+ transition remains to be a challenge. The highest ∼2.3 μm CW laser output power based on the 3H4 → 3H5 Tm3+ transition reported so far was only 1.89 W [14]. In addition to replacing host materials with one with better thermo-mechanical properties, another possible method to improve the ∼2.3 μm laser performance is using cascade lasing. As shown in Fig. 1(b), the intermediate metastable level |1 > is simultaneously the terminal laser level for |2> → |1> (|2>, higher-lying excited-state) and the emitting laser level for |1> → |0> (|0>, ground-state). If the fluorescence radiative lifetime of the |1 > is longer than that of the |2>, the |2> → |1 > transition can be of self-terminating nature (the bottleneck effect). By allowing the laser gain medium to simultaneously operate on the |1> → |0 > and |2> → |1 > transition, the intermediate metastable level |1 > will be efficiently depopulated, helping to avoid the bottleneck effect. This is the cascade lasing strategy, which is widely used in RE3+ with a metastable lower-lying excited-state, e.g. Tm3+ [15], Er3+ [16], Ho3+ [17,18], Dy3+ [19]. Recently, the diode-pumped cascade laser operation based on the Tm:YVO4 crystal (1.5 at.%) has been realized [20]. However, limited by the higher maximum phonon energy and the poor thermo-mechanical property, the maximum total CW laser output power was only 6.09 W, out of which the maximum ∼2.3 μm CW laser output power only reached 1.15 W with a lower slope efficiency of 7.9% and a higher laser threshold of 6.25 W [20]. Nevertheless, the results of this study demonstrate the potential advantages of vanadate crystals.
In the present work, we aimed to demonstrate the first efficient high-power diode-pumped Tm:GdVO4 laser simultaneously operating at ∼2 μm and ∼2.3 μm based on cascade lasing on the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transitions. Benefiting from the excellent properties of Tm:GdVO4 crystals, the Tm:GdVO4 laser generated the maximum total CW laser output power of > 8 W with a higher slope efficiency of 40% and a higher optical efficiency of 33.1%. The maximum ∼2.3 μm CW laser output power was 2.88 W with a slope efficiency of 14%, which is the highest CW laser output power amongst the laser diode (LD)-CW-pumped ∼2.3 μm Tm3+-doped lasers reported so far. The efficient high-power dual-waveband lasers simultaneously operating at ∼2 μm and ∼2.3 μm are promising for clinical medical treatment requiring real-time continuous non-invasive blood glucose monitoring [2–4,21,22], high-precision free-space telecommunications [23], and atmospheric environment monitoring supporting the detection of multiple gas components simultaneously [1].
2. Laser setup
Figure 2(a) shows the layout of the laser setup. To allow the high-power laser operation, the 794 ± 2 nm fiber-coupled AlGaAs LD with the maximum output power of 40 W was employed to excite the Tm:GdVO4 laser gain medium. The fiber core diameter and the numerical aperture of the used LD were 200 µm and 0.22, respectively. The output pump beam of the LD was collimated and focused into the Tm:GdVO4 crystal with a spot radius of 100 μm using a 1:1 combination lens with a focal length of 50 mm. The input mirror M1 was a flat mirror, which was coated for the high transmission (∼100%) at pump wavelength and high reflection (∼100%) at laser wavelength (1.8-2.4 μm). The output mirror M2 was a flat mirror, which was coated for the transmission of 2% at ∼2 μm and 1% at ∼2.3 μm (OC1), and 5% at ∼2 μm and 2% at ∼2.3 μm (OC2). In order to reduce the loss of the resonator and improve the laser output power, the distance between the M1 and M2 (cavity length) is compressed to ∼13 mm. The studied Tm:GdVO4 crystal (Tm3+ dopant concentration 1.5 at.%) grown by the conventional Czochralski method and oriented for light propagation along the a-axis was 10 mm thick with the aperture of 3.0 × 3.0 mm2. Both end faces were coated for anti-reflection at pump wavelength (792 ± 10 nm, reflection (R) < 0.5%) and laser wavelength (1850-2450 nm, R < 1%). It was worth noting that there was a mismatch between the emission wavelength of the LD (∼794 nm) and the absorption peak of the Tm:GdVO4 crystal (799.1 nm [7]). Therefore, a lower Tm3+ dopant concentration (<1.5 at.%) could be chosen when employing the 799.1 nm LD as the pump source, and it was promising to obtain a better laser performance due to the weaker CR process. The Tm:GdVO4 crystal was placed close to the M1. To remove the accumulated heat efficiently, the four sides of the Tm:GdVO4 crystal was wrapped by indium foil and embedded in a brass heat sink, which was water-cooled at 12 ℃. The residual pump beam passing through the M2 was filtered out from the output simultaneous dual-waveband CW laser by a long-pass filter (F1). Another long-pass filter (F2) coated for the transmission of ∼90% at ∼2.3 μm and almost zero transmission at ∼2 μm was used to separate the ∼2.3 μm power contribution. The laser emission spectra were measured using an optical spectrum analyzer (APE GmbH, Germany).
Fig. 2. (a) Schematic configuration of the diode-pumped cascade Tm:GdVO4 laser: LD, laser diode; M1, input mirror; M2, output coupler; F1 and F2, long-pass (LP) filter. (b) Measured pump absorption as a function of the incident pump power for non-lasing conditions.
First, the pump absorption efficiency under non-lasing conditions ηabs,NL for the Tm:GdVO4 crystal was initially measured by pump-transmission measurements. As shown in Fig. 2(b), with the increase in incident pump power, the pump absorption efficiency slowly decreased from 74% to 66%, indicating the effect of ground-state bleaching [24]. The pump absorption efficiency under lasing conditions ηabs,L can be determined according to the condition ηabs,L = ηabs,NL measured at the threshold pump power [24].
3. Experimental results and discussion
The laser performance of the diode-pumped cascade Tm:GdVO4 laser was studied based on the OC1 and OC2. Figure 3(a-b) shows the input-output dependences of the Tm:GdVO4 laser simultaneously operating on the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition. In this paper, we defined PΣ as the total CW laser output power, P2μm and P2.3μm as the CW laser output powers for the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition (PΣ = P2μm + P2.3μm), Pth,2μm and Pth,2.3μm as the laser thresholds for both Tm3+ transitions, ηΣ (η2μm and η2.3μm) as the corresponding laser slope efficiencies versus the absorbed pump power (Pabs), and X = P2.3μm / PΣ as the power fraction of the laser emission on the 3H4 → 3H5 Tm3+ transition.
Fig. 3. The input-output dependences of the diode-pumped cascade Tm:GdVO4 laser simultaneously operating on the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition for (a) OC1 and (b) OC2. (c) Power fraction X of the 3H4 → 3H5 Tm3+ transition.
For the transmission of the OC1 (TOC = 2% / 1%), the pump absorption efficiency under lasing conditions ηabs,L was measured to be 71.2% for the two Tm3+ transitions. As shown in Fig. 3(a), at the maximum absorbed pump power of 25.4 W, the cascade Tm:GdVO4 laser generated a maximum total CW laser output power PΣ of 7.76 W at ∼2 μm and ∼2.3 μm with a slope efficiency ηΣ of 33%, a laser threshold Pth,2μm (Pth,2.3μm) of 2.71 W, and an optical efficiency of 30.6%. For the 3F4 → 3H6 Tm3+ transition at ∼2 µm, the maximum CW laser output power P2μm reached 5.93 W with a slope efficiency η2μm of 25%. The laser emission on the 3H4 → 3H5 Tm3+ transition at ∼2.3 µm corresponded to 1.83 W (P2.3μm) and a slope efficiency η2.3μm of 9%.
For the transmission of the OC2 (TOC = 5% / 2%), the pump absorption efficiency under lasing conditions ηabs,L was measured to be 70.4% for the 3F4 → 3H6 Tm3+ transition and 70.35% for the 3H4 → 3H5 ones. The more excellent laser performance was obtained. At the maximum absorbed pump power of 25.4 W, the maximum total CW laser output power PΣ reached 8.42 W with a higher slope efficiency ηΣ of 40%, a higher optical efficiency of 33.1% (compared with OC1), and a laser threshold Pth,2μm of 4.07 W, as shown in Fig. 3(b). Further power scaling was limited by the available pump power. For the laser emission on the 3F4 → 3H6 Tm3+ transition, the Tm:GdVO4 laser generated a maximum CW laser output power P2μm of 5.55 W with a slope efficiency η2μm of 26%. The laser emission on the 3H4 → 3H5 Tm3+ transition corresponded to a higher maximum CW laser output power P2.3μm of 2.88 W with a higher slope efficiency η2.3μm of 14% (compared with OC1). The laser emissions on the two Tm3+ transitions have a similar laser threshold (Pth,2μm = 4.07 W and Pth,2.3μm = 4.20 W). There were excellent linear behavior and no thermal roll-over for both the total CW laser output power and the power contributions on the two Tm3+ transitions within the tested pump powers.
More details can be found in Table 1.
Table 1. Continuous wave output performancea of diode-pumped cascade Tm:GdVO4 laser.
The power fraction of the laser emission on the 3H4 → 3H5 Tm3+ transition for OC1 and OC2 was shown in Fig. 3(c). For the lower absorbed pump power slightly above the laser threshold, the power fraction was up to ∼90% (OC1) and ∼80% (OC2), respectively, and saturated for the absorbed pump power above 4.72 W, reaching X about 28% (OC1) and 34% (OC2). It indicated a non-competitive laser operation at the higher absorbed pump power between the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition.
For both OC1 and OC2, there was no thermal damage occurring in the Tm:GdVO4 crystal at the maximum incident pump power of 40 W during the long-term running of several hours. Furthermore, to the best of our knowledge, the ∼2.3 μm CW laser output power of 2.88 W obtained with OC2 is the highest one amongst the LD/TS (Ti:Sapphire)-CW-pumped ∼2.3 μm Tm3+-doped lasers reported so far, as shown in Fig. 4. Although the radiative lifetime and the luminescence lifetime of 3H4 state in the Tm:GdVO4 crystal is shorter than that of other crystals (see Table 2), the more excellent laser performance could be obtained by the Tm:GdVO4 crystal. We believe there could be three reasons. (I) Compared with Tm:YVO4, Tm:LuVO4, and most other commonly used crystals (Tm:YAG, Tm:YAP, and Tm:YLF), the Tm:GdVO4 crystal possesses the more excellent thermo-mechanical properties, such as the higher thermal conductivity and the lower thermal expansion coefficient, see Table 3, which is necessary for high-power lasers. (II) The lower maximum phonon energy (compared with YVO4 and LuVO4 crystal) and the higher absorption cross-section (compared with Tm:YAP, Tm:YAG, Tm:YLF, and Tm:YVO4 crystal) of the Tm:GdVO4 crystal facilitate a lower laser threshold for 3H4 → 3H5 Tm3+ transition and a higher laser slope efficiency, as shown in Table 1. (III) As shown in Fig. 1(a), for 3H4 → 3H5 Tm3+ transition, the terminal laser level 3H5 rapidly depopulated by the efficient multi-phonon NR relaxation, so that the ions are accumulated in the 3F4 (metastable lower-lying excited-state) with a long lifetime, naturally avoiding the bottleneck effect. Cascade lasing strategy allowing the simultaneous operation of 3H4 → 3H5 and 3F4 → 3H6 Tm3+ transition can help form population inversion for the 3H4 → 3H5 Tm3+ transition as well as avoid excessive bleaching of the ground-state.
Fig. 4. Performance comparison of the reported LD/TS-CW-pumped ∼2.3 μm Tm3+-doped lasers [14, 24–32].
Table 2. Radiative lifetime, luminescence lifetime, and emission quantum yield of 3H4 state.a
Table 3. The properties comparison of RE3+-doped laser crystals.a
Figure 5 shows the typical spectra of the cascade Tm:GdVO4 laser captured at different absorbed pump power for OC1 and OC2.
Fig. 5. The dual-waveband CW laser spectra of the diode-pumped cascade Tm:GdVO4 laser captured at different absorbed pump powers (Pabs): (a) OC1 and (b) OC2.
For the transmission of the OC1, as shown in Fig. 5(a), around the laser threshold (Pabs = 3.16 W), the Tm:GdVO4 laser operated at a single line around 1936nm and 2281 nm for 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition, respectively. With the increase in absorbed pump power, multiple longitudinal laser modes were generated (1931-1948nm, 2277-2286 nm at Pabs = 9.24 W, 1933-1953nm, 2280-2291 nm at Pabs = 12.5 W, and 1924-1947nm, 2276-2284 nm at Pabs = 18.9 W). The pump power dependence of the laser wavelength at ∼2 μm was caused by the change of the inversion fraction with the increase in pump power [47,48]. The phenomenon of the multiple laser emission lines was caused by the linear expansion affecting etalon (Fabry- Perot) effect at the interface between the Tm:GdVO4 crystal and the mirrors [25], as well as the relatively broad gain spectra of Tm:GdVO4 crystal (>200 nm for 3F4 → 3H6 Tm3+ transition) [7].
For the transmission of the OC2, as shown in Fig. 5(b), a similar spectra behavior was observed. Compared with OC1 with a lower transmission, the ∼2 μm laser emission on the 3F4 → 3H6 Tm3+ transition was significantly blue-shifted, e.g. from 1923-1947nm to 1910-1917nm at the absorbed pump power of 18.9 W. This behavior is well known for quasi-three-level Tm3+-doped lasers and is related to decreasing reabsorption losses at higher inversion in the gain medium associated with the higher transmittance of OC2. For the quasi-four-level 3H4 → 3H5 Tm3+ transition, as expected, the spectral position of the laser lines was almost independent of the output couplers.
4. Conclusions
To conclude, the Tm:GdVO4 crystal is a promising laser gain medium for the diode-pumped efficient high-power cascade laser simultaneously operating on the 3F4 → 3H6 and 3H4 → 3H5 Tm3+ transition. The maximum total laser output power reached 8.42 W with a slope efficiency of 40% and a laser threshold of 4.07 W, out of which the maximum ∼2.3 μm CW laser output power reached 2.88 W with a slope efficiency of 14% and a laser threshold of 4.20 W. The excellent laser performance was provided by the excellent higher thermal conductivity, lower thermal expansion coefficient, and larger absorption cross-section of the Tm:GdVO4 crystal. The power fraction of the laser emission on the 3H4 → 3H5 Tm3+ transition was almost constant, indicating the non-competitive laser operation in the cascade Tm:GdVO4 laser. The dual-waveband laser emission with a large wavelength separation based on the Tm3+ in the GdVO4 crystal could help to simultaneously address different applications. Future work will continue to focus on the power scaling by optimizing the Tm3+ dopant concentration, the pump power, the pump wavelength, or selecting the dual-end pumping as the new pump patten. Besides, the Q-switched and mode-locked laser will be also considered in our future work
Funding
National Natural Science Foundation of China (52072351, 12004213, 12174223, 12274263, 21872084, 62175128); Qilu Young Scholar Program of Shandong University; Taishan Scholar Foundation of Shandong Province.
Disclosures
The authors declare no conflicts of interest.
Data availability
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
References
1. M. E. Webber, J. Wang, S. T. Sanders, D. S. Baer, and R. K. Hanson, “In situ combustion measurements of CO, CO2, H2O and temperature using diode laser absorption sensors,” Proc. Combust. Inst. 28(1), 407–413 (2000). [CrossRef]
2. H. G. Piper, J. L. Alexander, A. Shukla, F. Pigula, J. M. Costello, P. C. Laussen, T. Jaksic, and M. S. D. Agus, “Real-time continuous glucose monitoring in pediatric patients during and after cardiac surgery,” Pediatrics 118(3), 1176–1184 (2006). [CrossRef]
3. B. Kalmovich, Y. Bar-Dayan, M. Boaz, and J. Wainstein, “Continuous glucose monitoring in patients undergoing cardiac surgery,” Diabetes Technol. Ther. 14(3), 232–238 (2012). [CrossRef]
4. T. Okada, S. Kawahito, N. Mita, M. Matsuhisa, H. Kitahata, M. Shimada, and S. Oshita, “Usefulness of continuous blood glucose monitoring and control for patients undergoing liver transplantation,” J. Med. Investig. 60(3.4), 205–212 (2013). [CrossRef]
5. V. Petrov, “Frequency down-conversion of solid-state laser sources to the mid-infrared spectral range using non-oxide nonlinear crystals,” Prog. Quantum Electron. 42, 1–106 (2015). [CrossRef]
6. T. Popmintchev, M. Chen, D. Popmintchev, et al., “Bright coherent ultrahigh harmonics in the keV X-ray regime from midinfrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012). [CrossRef]
7. J. Šulc, P. Koranda, P. Černý, H. Jelínková, Y. Urata, M. Higuchi, W. Ryba-Romanowski, R. Lisiecki, P. Solarz, G. Dominiak-Dzik, and M. Sobczyk, “Tunable lasers based on diode pumped Tm-doped vanadates Tm:YVO4, Tm:GdVO4, and Tm:LuVO4,” Proc. SPIE 6871, 68711V (2008). [CrossRef]
8. Y. Sato and T. Taira, “Thermo-optical and -mechanical parameters of Nd:GdVO4 and Nd:YVO4,” in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies 2007 Technical Digest, Optical Society of America, Washington, D.C., May 2007.
9. P. A. Loiko, K. V. Yumashev, V. N. Matrosov, and N. V. Kuleshov, “Dispersion and anisotropy of thermo-optic coefficients in tetragonal GdVO4 and YVO4 laser host crystals: erratum,” Appl. Opt. 54(15), 4820–4822 (2015). [CrossRef]
10. G. L. Bourdet and G. Lescroart, “Theoretical modelling and design of a Tm:YVO4 microchip laser,” Opt. Commun. 149(4-6), 404–414 (1998). [CrossRef]
11. Y. Kalisky, The Physics and Engineering of Solid State Lasers (Bellingham, Washington, 2005).
12. M. Schellhorn, “High-power diode-pumped Tm:YLF laser,” Appl. Phys. B 91(1), 71–74 (2008). [CrossRef]
13. E. C. Honea, R. J. Beach, S. B. Sutton, J. A. Speth, S. C. Mitchell, J. A. Skidmore, M. A. Emanuel, and S. A. Payne, “115-W Tm:YAG diode-pumped solid-state laser,” IEEE J. Quantum Electron. 33(9), 1592–1600 (1997). [CrossRef]
14. X. Yu, H. Chu, F. Zha, H. Pan, S. Zhao, Z. Pan, and D. Li, “Watt-level diode-pumped Tm:YVO4 laser at 2.3 µm,” Opt. Lett. 47(21), 5501–5504 (2022). [CrossRef]
15. S. Tessarin, M. Lynch, J. F. Donegan, and G. Mazé, “Tm3+-doped ZBLAN fibre amplifier at 1.49 µm with co-operative lasing at 1.88 µm,” Electron. Lett. 41(16), 899–900 (2005). [CrossRef]
16. B. Schmaul, G. Huber, R. Clausen, B. Chai, P. LiKamWa, and M. Bass, “Er3+:YLiF4 continuous wave cascade laser operation at 1620 and 2810 nm at room temperature,” Appl. Phys. Lett. 62(6), 541–543 (1993). [CrossRef]
17. L. Esterowitz, R. C. Eckardt, and R. E. Allen, “Long-wavelength stimulated emission via cascade laser action in Ho:YLF,” Appl. Phys. Lett. 35(3), 236–239 (1979). [CrossRef]
18. S. Ye, X. Zhou, S. Huang, H. Nie, J. Bian, T. Li, K. Yang, J. He, and B. Zhang, “Cascade MIR Ho:YLF laser at 2.1 µm and 2.9 µm,” Opt. Lett. 47(21), 5642–5645 (2022). [CrossRef]
19. S. Sujecki, L. Sójka, E. Bereś-Pawlik, Z. Tang, D. Furniss, A. B. Seddon, and T. M. Benson, “Modelling of a simple Dy3+ doped chalcogenide glass fibre laser for mid-infrared light generation,” Opt. Quantum Electron. 42(2), 69–79 (2010). [CrossRef]
20. X. Yu, Z. Pan, H. Chu, F. Zha, H. Pan, L. Ma, P. Loiko, P. Camy, and D. Li, “Cascade lasing at ∼2 μm and ∼2.3 μm in a diode-pumped Tm:YVO4 laser,” Opt. Express 31(9), 13576–13584 (2023). [CrossRef]
21. K. Kawahito, H. Sato, M. Kadosaki, A. Egawa, and Y. Misawa, “Spike in glucose levels after reperfusion during aortic surgery: assessment by continuous blood glucose monitoring using artificial endocrine pancreas,” Gen. Thorac. Cardiovasc. Surg. 66(3), 150–154 (2018). [CrossRef]
22. Y. Sugiyama, C. Kiuchi, M. Suzuki, Y. Maruyama, R. Wakabayashi, Y. Ohno, S. Takahata, T. Shibazaki, and M. Kawamata, “Glucose management during insulinoma resection using real-time subcutaneous continuous glucose monitoring,” Case Rep. Anesthesiol. 2018, 1–4 (2018). [CrossRef]
23. J. Li, H. Luo, L. Wang, Y. Liu, Z. Yan, K. Zhou, L. Zhang, and S. K. Turistsyn, “Mid-infrared passively switched pulsed dual wavelength Ho3+-doped fluoride fiber laser at 3 μm and 2 μm,” Sci. Rep. 5(1), 10770 (2015). [CrossRef]
24. E. Kifle, P. Loiko, L. Guillemot, J.-L. Doualan, F. Starecki, A. Braud, T. Georges, J. Rouvillain, and P. Camy, “Watt-level diode-pumped thulium lasers around 2.3 μm,” Appl. Opt. 59(25), 7530–7539 (2020). [CrossRef]
25. L. Guillemot, P. Loiko, E. Kifle, J.-L. Doualan, A. Braud, F. Starecki, T. Georges, J. Rouvillain, A. Hideur, and P. Camy, “Watt-level mid-infrared continuous-wave Tm:YAG laser operating on the 3H4 → 3H5 transition,” Opt. Mater. 101, 109745 (2020). [CrossRef]
26. F. Wang, H. Huang, F. Wu, H. Chen, Y. Bao, Z. Li, O. L. Antipov, S. S. Balabanov, and D. Shen, “2.3-2.5 μm laser operation of LD-pumped Tm:YAP on the 3H4 → 3H5 transition,” Opt. Mater. 115, 111054 (2021). [CrossRef]
27. L. Guillemot, P. Loiko, A. Braud, J.-L. Doualan, A. Hideur, M. Koselja, R. Moncorge, and P. Camy, “Continuous-wave Tm:YAlO3 laser at ∼2.3 μm,” Opt. Lett. 44(20), 5077–5080 (2019). [CrossRef]
28. S. Wang, H. Huang, H. Chen, X. Liu, S. Liu, J. Xu, and D. Shen, “High efficiency nanosecond passively Q-switched 2.3 μm Tm:YLF laser using a ReSe2-based saturable output coupler,” OSA Continuum 2(5), 1676–1682 (2019). [CrossRef]
29. A. Muti, M. Tonelli, V. Petrov, and A. Sennaroglu, “Continuous-wave mid-infrared laser operation of Tm3+:KY3F10 at 2.3 μm,” Opt. Lett. 44(13), 3242–3245 (2019). [CrossRef]
30. L. Guillemot, P. Loiko, R. Soulard, A. Braud, J.-L. Doualan, A. Hideur, and P. Camy, “Close look on cubic Tm:KY3F10 crystal for highly efficient lasing on the 3H4 → 3H5 transition,” Opt. Express 28(3), 3451–3463 (2020). [CrossRef]
31. P. Loiko, E. Kifle, L. Guillemot, J.-L. Doualan, F. Starecki, A. Braud, M. Aguiló, F. Díaz, V. Petrov, X. Mateos, and P. Camy, “Highly efficient 2.3 μm thulium lasers based on a highphonon-energy crystal: evidence of vibronic-assisted emissions,” J. Opt. Soc. Am. B 38(2), 482–495 (2021). [CrossRef]
32. H. Huang, S. Wang, H. Chen, O. L. Antipov, S. S. Balabanov, and D. Shen, “High power simultaneous dual-wavelength CW and passively-Q-switched laser operation of LD pumped Tm:YLF at 1.9 and 2.3 μm,” Opt. Express 27(26), 38593–38601 (2019). [CrossRef]
33. P. Loiko, R. Soulard, L. Guillemot, G. Brasse, J.-L. Doualan, A. Braud, A. Tyazhev, A. Hideur, F. Druon, and P. Camy, “Efficient Tm:LiYF4 lasers at ∼2.3 μm: effect of energy-transfer upconversion,” IEEE J. Quantum Electron. 55(6), 1700212 (2020). [CrossRef]
34. R. Lisiecki, P. Solarz, G. Dominiak-Dzik, W. Ryba-Romanowski, M. Sobczyk, P. Černý, J. Šulc, H. Jelínková, Y. Urata, and M. Higuchi, “Comparative optical study of thulium-doped YVO4, GdVO4, and LuVO4 single crystals,” Phys. Rev. B 74(3), 035103 (2006). [CrossRef]
35. F. S. Ermeneux, C. Goutaudier, R. Moncorge, M. T. Cohen-Adad, M. Bettinelli, and E. Cavalli, “Growth and fluorescence properties of Tm3+ doped YVO4 and Y2O3 single crystals,” Opt. Mater. 8(1-2), 83–90 (1997). [CrossRef]
36. Q. Dong, G. Zhao, J. Chen, Y. Ding, and C. Zhao, “Growth and anisotropic thermal properties of biaxial Ho:YAlO3 crystal,” J. Appl. Phys. 108(2), 023108 (2010). [CrossRef]
37. Y. Lu, Y. Dai, Y. Yang, J. Wang, A. Dong, and B. Sun, “Anisotropy of thermal and spectral characteristics in Tm:YAP laser crystals,” J. Alloys Compd. 453(1-2), 482–486 (2008). [CrossRef]
38. T. M. Pollak, W. F. Wing, R. J. Grasso, E. P. Chicklis, and H. P. Jenssen, “CW laser operation of Nd:YLF,” IEEE J. Quantum Electron. 18(2), 159–163 (1982). [CrossRef]
39. F. Canbaz, I. Yorulmaz, and A. Sennaroglu, “2.3-μm Tm3+:YLF laser passively Q-switched with a Cr2+:ZnSe saturable absorber,” Opt. Lett. 42(9), 1656–1659 (2017). [CrossRef]
40. I. Razumova, A. Tkachuk, A. Nikitichev, and D. Mironov, “Spectral-luminescent properties of Tm:YLF crystal,” J. Alloys Compd. 225(1-2), 129–132 (1995). [CrossRef]
41. Y. Song, N. Zong, Z. Chen, X. Wang, Y. Bo, and Q. Peng, “Temperature-dependent thermal, spectroscopic properties, and laser performance of Nd:YVO4 crystal,” Appl. Phys. B 129(5), 72 (2023). [CrossRef]
42. H. Zhang, L. Zhu, X. Meng, Z. Yang, C. Wang, W. Yu, Y. Chow, and M. Lu, “Thermal and laser properties of Nd:YVO4 crystal,” Cryst. Res. Technol. 34(8), 1011–1016 (1999). [CrossRef]
43. D. Ran, H. Xia, S. Sun, F. Liu, Z. Ling, W. Ge, H. Zhang, and J. Wang, “Thermal properties of a Nd:LuVO4 crystal,” Cryst. Res. Technol. 42(9), 920–925 (2007). [CrossRef]
44. P. Rafailov, D. Dimitrov, Y.-F. Chen, C.-S. Lee, and J.-Y. Juang, “Symmetry of the optical phonons in LuVO4: A Raman study,” Crystals 10(5), 341 (2020). [CrossRef]
45. L. Qin, X. Meng, H. Shen, L. Zhu, B. Xu, L. Huang, H. Xia, P. Zhao, and G. Zheng, “Thermal conductivity and refractive indices of Nd:GdVO4 crystals,” Cryst. Res. Technol. 38(9), 793–797 (2003). [CrossRef]
46. H. Zhang, X. Meng, L. Zhu, and Z. Yang, “Growth and thermal properties of Nd:GdVO4 single crystal,” Mater. Res. Bull. 34(10-11), 1589–1593 (1999). [CrossRef]
47. O. L. Antipov, Y. A. Getmanovskiy, S. S. Balabanov, S. V. Larin, and V. V. Sharkov, “1940nm, 1966nm and 2066nm multi-wavelength CW and passively-Q-switched operation of L-shaped Tm3+:Lu2O3 ceramic laser in-band fiber-laser pumped at 1670 nm,” Laser Phys. Lett. 18(5), 055001 (2021). [CrossRef]
48. O. L. Antipov, “High efficiency in-band pumped Tm- and Ho-doped 2-μm solid-state lasers,” J. Phys.: Conf. Ser. 2494(1), 012009 (2023). [CrossRef]
