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  • BBO Pockels Cells
  • BBO Pockels Cells

BBO Pockels Cells

  • High Repetition Rate and Damage Resistance
  • Low Absorption and Acoustic Noise 
  • High Ultra-Violet Transmission
  • Pockels Cells with Double Crystals available
  • Applications: High repetition rate DPSS Q-switches, High Repetition Rate Regenerative Amplifier Control, Cavity Dumping and Beam Chopper
  • To check the stock list of BBO Pockels Cells, please click here
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Specifications of BBO Pockels cells

Aperture TBA Quarter-wave voltage 3.4KV
Optical Transmission >98% Damage Threshold 500MW/cm2 @ 10ns, 1064nm
Wavefront Distortion @ 1064 < Lambda/8 Typical Capacitance < 3pF
Outline Dimension φ25.4 x 44mm


Physical properties of BBO:

Crystalline structure Trigonal, space group R3c, Point group 3m Cell Parameters a = b = 12.532 Å, c = 12.717Å, Z = 6
Melting point1095±5℃Phase transition point925±5℃
Optical Homogeneityδn ~ 10-6 /cmMohs hardness4
Density3.85 g/cm3Specific heat1.91J/cm3 xK
HydroscopicityLowThermal expansion coefficientsa,4 x 10-6/K;c, 36x 10-6/K
Thermal Conductivity⊥c,1.2W/m/K; //c, 1.6W/m/KAbsorption Coefficient< 0.1% /cm (at 1064 nm)


Optical properties of BBO:

Transparency Range189-3500 nmRefractive Indices
at 1064 nm
at 800 nm
at 532 nm
at 400 nm
at 266 nm

no = 1.6545, ne = 1.5392
no = 1.6606, ne = 1.5444
no = 1.6742, ne = 1.5547
no = 1.6930, ne = 1.5679
no = 1.7585, ne = 1.6126
Thermo-optic Coefficientsdno/dT = -9.3 x 10-6 /°C
dne/dT = -16.6 x 10-6 /°C
Electro-optic Coefficientsγ11 = 2.7 pm/V, γ22, γ31 < 0.1 γ11
Effective Nonlinearity Expressionsdooe= d31 sinθ +(d11 cos3φ - d22 sin3φ) cosθ
deoe= (d11 sin3φ + d22 cos3φ) cos2θ
Half-wave Voltage48 kV (at 1064 nm)
NLO Coefficientsd11 = 5.8 x d36(KDP)
d31 = 0.05 x d11
d22 < 0.05 x d11
Damage Threshold (Bulk)
at 1064 nm
at 532 nm

5 GW/cm2 (10 ns); 10 GW/cm2 (1.3 ns)
1 GW/cm2 (10 ns); 7 GW/cm2 (250 ps)
Phase-matchable SH Wavelengths:189 - 1750 nm

Beta BBO Pockels Cells or beta barium borate pockels cells exhibit significant advantages over other materials in terms of laser power handling abilities, temperature stability, and substantial freedom from piezoelectric ringing. Beta BBO Pockels cells are the most attractive candidates for high repetition rate Q-switching, pulse picking at up to 3 MHz, laser cavity dumping, regenerative amplifier control and beam chopper. BBO pockels cells are the better option than KDP pockels cells in the field of high repetition rate and high power applications. And on account for the low piezoelectric coupling coefficients of BBO, our cells could generate pulses with repetition rates of hundreds of kilohertz.

Hangzhou Shalom EO offers the off-the-shelf and custom BBO Pockels Cells with high damage threshold, low insertion loss, high extinction ratio, minimal piezoelectric ringing and competitive price. BBO Pockels Cells with both Single and double BBO crystal design and low -voltage geometry are available upon requests. Besides, we also offer BBO crystals for EO applications.

To check the stock list of BBO Pockels Cells, please click here

Click Here to visit our archives to learn more about pockels cells.


Features:

  • They are the best choice for high repetition rate Q-switching:

Because it relies on the electro-optical effect, switching time - aided by the low capacitance of the Electro-Optical Q Switch is very fast, therefore it has surpassing performance for high repetition rate lasers up to 1MHz. All-solid-state short-cavity Q-switched laser using BBO electro-optic Q-switch can generate high-energy laser with a pulse width of less than 4ns.

  •  High damage threshold and power handling capability:

Without water cooling, the BBO electro-optical Q switch can be turned off and withstand up to 150W intracavity oscillation optical power (laser output power up to 50W).

  •  Wide Transmission range from UV to NIR:

BBO crystals has a wide transparency range of 189nm to 3500nm, which allows it to be used in diverse applications from UV to NIR spectrum. 

  •  Low Absortion and piezoelectric ringing:

Comparing to LiNbo3, BBO crystals are much less impaired by piezoelectric when voltage is applied. The other important feature of BBO electro-optics is their very low absorption and associated laser-induced thermal birefringence. Due to the low absorption, very little optical heating will occur at operating wavelengths in the visible and near IR.

  • Relatively high half wave voltage:

BBO has a comparatively small electro-optic coefficient, and hence high applying voltage.Shalom EO offers customized BBO crystals with required dimensions as well. BBO has a comparatively small electro-optic coefficient, and hence high applying voltage.Shalom EO offers customized BBO Pockels Cells with required dimensions as well. Our panel of engineers could offer professional consultancy and help you ascertain the optimized solution for your need.


 Cautions:

  • BBO crystals are hydroscopic and therefore it is recommended to preserve and use them in dry environment.
  • Precautions need to be taken to protect its polished surfaces since BBO is comparatively vulnerable.
  • The acceptance angle of BBO is small, so be careful when it comes to adjusting angles.
  • Hangzhou Shalom EO engineers can offer you the best suitable and high quality Pockels Cell according to the characteristics of your lasers. The parameters we take into concern include pulse width , energy per pulse, repetition rate for a pulsed laser, power for a cw laser, divergence, laser beam diameter, wavelength tuning range, mode condition, etc.

Features of BBO crystal

  • Ultra-thin crystals can be used for ultra-fast (<10 fs) applications
  • Wide phase matching range of various second-order nonlinear interactions in almost the entire transparent range
  • The highest nonlinearity among all UV nonlinear crystals
  • High laser induced damage threshold (LIDT)
  • Wide transmittance range from 188 nm to 5.2μm (appropriate transparency @3μm-5.2μm, tens of μm thick crystal)
  • Extremely low capacitance (1< pF) will permit high repetition rate switching with rise times on the order of 100 ps or less
  • High damage threshold capable of withstanding high peak power intensities of samller beam size and therefore suitable for compact design ( However, small crystal aperture leads to diffraction losses and hence might increase the insertion losses.)
  • Not prone to piezo-electric ringing
  • Low absorption and associated laser-induced thermal birefringence
  • High extinction ratio

Applications:

  1. High repetition rate DPSS Q-switches
  2. High repetition rate regenerative amplifier control
  3. Cavity dumping and Beam chopper
  4. Low dispersion suitable for short pulse regenerative amplifiers




          


Fig.1  Qualitative comparison of acoustic ringing in BBO and LiNbO3 

                         The intensity transmitted through the LiNbO3 Pockels cell varies greatly due to piezoelectric effects, whereas the light transmitted through the

                         BBO Pockels cell follows the decay of the applied high voltage pulse with no evident acoustic ringing

                                                                                                   

                                                                                                                                     Fig.2 Transparency Curve of BBO crystal



Application Notes:

Side physical effects of Pockels cells:

When it comes to practical applications of Pockels cells, one may need to take some additional side effects into account:

  • Etalon effects may still exists and affect the optical performance if the beam direction is perpendicular to the faces of crystal, Even when the end faces of the crystal are coated with high-quality AR coatings.
  • Temperature could significantly affect the obtain phase changes.For example, a Pockels cell which is set to generate perfect high-contrast amplitude modulation, may require readjustments of the operation voltages when the temperature changes. However there are thermally compensated double crystal designs may circumvent the problem.
  • For operation with large beam radius, it is worth paying attention to sort out an optimized design for electrodes (possibly with additional auxiliary electrodes for high uniformity of the generated electric field, as otherwise one may obtain a spatially varying modulation).
  • Nonlinear crystals often exhibit substantial piezo-electric and elastooptic effects, which can have substantial influences on the performance at high modulation frequencies.
  • Operating at high power levels, thermal effects may be induced by residual absorption of the crystal . Therefore materials with lower absorption are preferable for high power applications
  • The crystals used in Pockels cells are nonlinear crystal materials, they inherently demonstrates considerable optical nonlinearities. For instance, self-phase modulation and nonlinear self-focusing might occur for light pulses with substantial peak power.

Calculation of Quarter-wave Voltage

The voltage required to produce a retardance of π radians is called the halfwave voltage or simply Vπ. For an optical input linearly polarized 45o applying a halfwave voltage rotates the polarization by 90o. When the output wave is passed through a linear the resultant can be rapidly modulated from maximum intensity to minimum intensity by rapidly changing the voltage applied to the crystal from 0 volts to Vπ.

The halfwave voltage of BBO is dependent on the optical wavelength and is given by:

Where   λ=optical wavelength 
         d=electrode spacing 
         L=optical path length 
         r22=electro-optic coefficients 
         no=ordinary indices of refraction

 


EO Q-Switch 1/4Wave Voltage Vs wavelength (3x3x20mm) 
1/4 Wave Voltage @1030nm : Vπ/2 =3388V