1. <rp id="b54kh"><object id="b54kh"><input id="b54kh"></input></object></rp>
      1. <dd id="b54kh"><center id="b54kh"></center></dd>

        1. <button id="b54kh"><acronym id="b54kh"><input id="b54kh"></input></acronym></button>

              <th id="b54kh"></th>

                1. eo_logo
                  • 選擇國家或地區
                  • ,您好! 我的帳戶
                  • cart   
                  Characteristics of 2μm Lasers

                  Characteristics of 2µm Lasers

                  Lasers with a wavelength of 2μm have advanced significantly in recent years and offer high efficiency, stability, and ease of use. 2μm lasers are ideal for highly precise applications including medical surgery and plastic processing because of their unique absorption characteristics, which allow them to create very small and precise cuts in both biological tissue and plastics with minimal localized heating. The absorption characteristics of 2μm lasers give them an advantage over 1μm lasers for certain applications.

                  Laser Design

                  The first 2μm lasers were very large, expensive, liquid-nitrogen cooled devices. Today there are 2μm diode lasers 30mm long and fiber lasers that are even smaller. Due to their inherent user-friendliness and broad range of energy delivery, including both pulsed and continuous wave (CW), 2μm lasers will improve efficiency and enable new procedures in various applications. Advances in technology are driving down costs and decreasing the size, while simultaneously improving performance. In some cases, researchers are developing components out of optical fibers, which can dramatically decrease the cost.

                  Laser Operation, Elements, and Power

                  For 2μm lasers, two rare earth elements have proven to be laser gain dopants that provide high power for both CW and pulsed laser operation: Thulium (Tm3+) and Holmium (Ho3+). The ions from these elements achieve laser emission in many different host crystals and glass fibers (see Table 1). For CW operation, thulium lasers proved a better option, while holmium proved better for pulsed and q-switched lasers due to the higher gain of the holmium-doped crystals. Thulium lasers are also advantageous because the ions can be excited with commercially available laser diodes around 800nm, while holmium can only be excited by a 1.9μm pump source.

                  2μm lasers with average powers around 100W are ideal for a number of industrial processes. Table 1 shows powers achieved by thulium-doped lasers and table 2 show powers achieved by holmium-doped lasers.

                  Laser Host Material Pump  Wavelength (nm) Emission Wavelength (nm) CW Output Power (W) Slope Efficiency (%)
                  YAG 805 2013 115 52
                  YAG 800 2013 120 Not Reported
                  YLF 792 1910 55 49
                  YLF 790 1912 148 32.6
                  LuO3 796 2070 1.5 61
                  Germanate 800 1900 64 68
                  Silica Fiber 793 2050 110 55
                  Silica Fiber 1567 1940 415 60
                  Silica Fiber 790 2040 885 49.2
                  Table 1: Published output powers, pump wavelengths, and emission wavelengths for CW thulium-doped lasers (Scholle et al., 2010).
                  Laser Host Material Pump Source Pump
                  Wavelength (μm)
                  Emission Wavelength (nm) CW Output Power (W) Pulse Energy (mJ) Slope Efficiency (%)
                  Ho:YAG Tm: YL 1.95 2090 1.6 Not Reported 21
                  Ho:YAG Tm:YLF 1.9 2090 Not Reported 50 Not Reported
                  Ho:YAG Tm Fiber 1.905 2097 6.4 Not Reported 80
                  Ho:YLF Tm Fiber 1.94 2050 43 40 42
                  Ho:YAG Tm Fiber 1.908 2100 10 15 52
                  Ho:YAG Tm:YLF 1.908 2090 9.4 Not Reported 40
                  Ho:YAG Tm:YLF 1.91 2100 14 Not Reported 16
                  Ho:YAG Diode 1.91 2120 40 3.5 57
                  Ho:YAF Tm Fiber 1.94 2065 12.4 10.9 47
                  Ho:YAG Tm Fiber 1.908 2090 18.7 Not Reported 80
                  Table 2: Published output powers, pump wavelengths, and emission wavelengths for holmium-doped lasers (Scholle et al., 2010). 

                  Eye Safety

                  2μm wavelengths are included in the wavelength range deemed safe for eyes, which starts around 1.4μm. This range is deemed safe to the eye because laser radiation around 1.4μm-2.4μm is strongly absorbed in the vitreous body of the eye and does not reach the retina, which is responsible for sending nerve impulses to the brain. In addition, the intensity threshold for irreversible eye damage is much higher around 2μm than for shorter wavelengths, such as 1μm. While the user-friendly design and protection of the retina are beneficial, 2μm beams can also damage other parts of the eye besides the retina, requiring all laser safety precautions to still be taken.

                  Compatible Optical Materials

                  Optical materials with good transmission in the 2μm spectral range each have their own unique advantages that lend to various applications. Zinc Selenide (ZnSe) is arguably the most preferred material for lenses, windows, output couplers, and laser beam expanders operating at 2μm for its low absorptivity at infrared wavelengths and visible transmission. Transmission in the visible spectrum allows for a visible guide beam to be used along with a 2μm beam. Calcium Fluoride (CaF2) is another substrate option for 2μm lasers because its transmission is above 90% between 0.25-7μm, it is available in large sizes, and it is cheaper than similar substrates such as barium fluoride (BaF2). Other substrates that transmit at 2μm include IR-grade fused silica, germanium, magnesium fluoride (MgF2), N-BK7, potassium bromide (KBr), sapphire, silicon, sodium chloride (NaCl), and clear-grade zinc sulfide (also known as Cleartran?).

                  IR Material Comparison
                  NameProperties / Typical Applications
                  Calcium Fluoride (CaF2) Low Absorption, High Refractive Index Homogeneity
                  Used in Spectroscopy, Semiconductor Processing, Cooled Thermal Imaging
                  Fused Silica (FS) Low CTE and Excellent Transmission in IR
                  Used in Interferometry, Laser Instrumentation, Spectroscopy
                  Germanium (Ge) High nd, High Knoop Hardness, Excellent MWIR to FIR Transmission
                  Used in Thermal Imaging, Rugged IR Imaging
                  Magnesium Fluoride (MgF2) High CTE, Low Index of Refraction, Good Transmission from Visible to MWIR
                  Used in Windows, Lenses, and Polarizers that Do Not Require Anti-Reflection Coatings
                  N-BK7 Low-Cost Material, Works Well in Visible and NIR Applications
                  Used in Machine Vision, Microscopy, Industrial Applications
                  Potassium Bromide (KBr) Good Resistance to Mechanical Shock, Water Soluble, Broad Transmission Range
                  Used in FTIR spectroscopy
                  Sapphire Very Durable and Good Transmission in IR
                  Used in IR Laser Systems, Spectroscopy, and Rugged Environmental Equipment
                  Silicon (Si) Low Cost and Lightweight
                  Used in Spectroscopy, MWIR Laser Systems, THz Imaging
                  Sodium Chloride (NaCl) Water Soluble, Low Cost, Excellent Transmission from 250nm to 16μm, Sensitive to Thermal Shock
                  Used in FTIR spectroscopy
                  Zinc Selenide (ZnSe) Low Absorption, High Resistance to Thermal Shock
                  CO2 Laser Systems and Thermal Imaging
                  Zinc Sulfide (ZnS) Excellent Transmission in Both Visible and IR, Harder and More Chemically Resistant than ZnSe
                  Used in Thermal Imaging
                  Table 3: Comparison of the properties of common IR substrates.

                  To learn more about the promising applications of 2μm laser optics, download the whitepapers below. 

                  2μm Medical Laser Applications
                  2μm Medical Laser Applications
                  2μm Materials Processing Applications
                  2μm Materials Processing Applications

                  Scholle, Karsten, Samir Lamrini, Philipp Koopmann, and Peter Fuhrberg. "2 μm Laser Sources and Their Possible Applications." InTechOpen. InTech, 01 Feb. 2010. Web.