HEM® Ti:Sapphire crystals are grown using the Heat Exchanger Method, (HEM). This unique method of growth allows for production of the world’s largest Ti:Sapphire crystals, with excellent optical and thermal properties. The growth of our crystals takes place in a reducing atmosphere in order to maximize Ti3+ ions, thereby reducing parasitic absorption and maximizing FOM (Figure of Merit) values. The superior homogeneity and low wave front distortion of our laser rods allow laser systems to reach high energy levels without sacrificing beam profile quality. Current production of amplifier crystals of over 200 mm in diameter are ensuring success at the next generation of high intensity laser facilities.

HEM® Ti:Sapphire

  • Excellent homogeneity
  • Superior Thermal Properties
  • High Figures of Merit (FOM)
  • No Bulk Scatter
  • High Laser Damage Threshold
  • Large sizes and highly doped material available


    • FOM (Figure Of Merit) Vs. Absorption – The HEM process has been designed to maximize the lasing characteristics of Ti:Sapphire thereby delivering the highest FOM values in the industry. Many companies claim to have high FOM values, however, they do not test the “actual” values as GT does. We measure FOM based on (absorption @ 514nm ) / (absorption @ 800nm).  Each GT Ti:Sapphire crystal is tested to verify FOM values and ensure that the intrinsic properties of our material are well suited to support your laser’s high performance.
    • Tunability Range of HEM Ti:Sapphire –  Ti:Sapphire has a wide tunable range from 650 nm to 1200 nm with peak intensity at ~800 nm. This tunable range gives customers a wide variety of wavelength options to maximize their laser performance for specific laser applications.  The wide bandwidth of the material allows for short pulses and high repetition rates.
    • Absorption / Fluorescence – Ti:Sapphire lasers are typically operated using π-polarization. This chart shows the absorption and fluorescence bands of Ti:Sapphire in π-polarization.
    • Brewster’s Cut Laser Crystal – Most of our smaller crystals are polished with Brewster’s angle ends to minimize reflection losses. Brewster’s angle is based on the index of refraction of the material. The index of refraction for Ti:Sapphire is ~1.76, resulting in ~60.4° Brewster’s angle. The C-axis rotation is also very important to maximize power in π-polarization. GT has developed a method to maintain accurate alignment of Brewster’s angle to the C-axis, thus improving lasing performance.
TiSapphire Brewster Cut Laser Crystal
    • Advanced polishing and coatings – We employ the most advanced polishing techniques in order to create ultra smooth surfaces with low sub-surface damage. We have performed testing of differently processed surfaces to ensure that laser damage threshold values are maximized.  Additionally, polishing processes have been optimized to support excellent transmitted wave front values.  By combining high quality material, the correct polishing techniques and optimized coatings, we provide the highest performance laser rods available.
    • Anti-Reflection Coating – GT offers advanced anti-reflection coatings for multipass amplifier crystals. Our coatings are engineered to provide maximum efficiency at peak power levels.  Our coatings are designed specifically for high power laser applications with minimum reflection losses at the pump beam and lasing beams. These coatings have shown consistently high laser damage threshold results allowing laser operators to calculate pump powers accurately, thereby maximizing power output with low risk of damage.


High quality Ti:Sapphire laser crystals begin with perfect crystalline structure and the correct 3+ valance electron state.  We ensure these requirements through our multiple-stage, rigorous inspection process, using state-of-the-art test and measurement equipment. We test our rods for absorption values, homogeneity, light scatter, FOM, flatness, and transmitted wave fronts. Each HEM laser rod is examined and verified utilizing advanced equipment and expert laser technicians. Total focus on quality and accuracy guarantees that our laser crystals dimensions, surfaces and crystalline structure provide the foundation for your laser platform’s high power levels and excellent beam profiles.


HEM Ti:Sapphire’s wide emission range, (660 nm to 1180 nm), high-power density pumping capability along with excellent crystalline structure enable today’s high intensity laser platforms.  The high intensity platforms utilize Ti:Sapphire because of high peak-power, short pulses, increasing repetition rates and excellent beam quality and control.  These facilities are creating the next generation of laser based applications such as radio therapy, proton therapy, accelerator physics, nuclear physics, infrared spectroscopy and materials characterization. GT works closely with its customers to promote new designs and technology for the advancement of high intensity lasers.


Laser Damage Threshold Testing of Ti Sapphire AR Coating

The test results below come from one of the periodic tests that CSI performs on the AR coating that is used on HEM Ti:Sapphire Amplifier Crystals. These results are representative of the damage threshold that can be expected with our coatings.

Test Sample

  • Test Type: laser damage threshold
  • Substrate Material: HEM Ti:Sapphire
  • Sample Size: 1″ diameter
  • Coating Type: AR

 Test Conditions

  • Test Wavelength: 532 nm
  • Angle of Incidence: 0º
  • Pulse Repetition Frequencies: 10 Hz
  • Polarization: linear
  • Test Beam Profile: TEM Pulsewidth, (FWHM): 10 ns Axial Modes: multiple S
  • Pit Diameter: 570 µm
  • Number of Sites: 80
  • Test Method: laser damage frequency
  • Exposure Duration: 200 shots/site

Test Results

  • Damage Definition: plasma, increased He-Ne scattering, visible damage as observed using a
    100X Nomarski Brightfield Microscope.
  • Description of Results: part irradiated at 13.00 Jcm-2 with no damage in 10 sites
  • Laser Damage Threshold: calculated at 14.16 Jcm-2 peak fluence
  • Testing provided by Spica Technologies Inc.

Features and Highlights

Laser Crystals up to 200 mm in diameter

Many design options including rectangles, squares and your unique designs

Low damage polished plano-ends, Brewster's angle ends

Highest laser damage threshold coatings available

Path lengths ranging from 1mm to 75mm

Absorption values from 0.5 to 10+ /cm @ alpha 514nm

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Contact one of our product experts to find out how crystals grown with our Heat Exchanger Method can benefit your company’s operations.
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