Top Notch BBO Crystal Manufacturing

BBO crystals are among the most flexible nonlinear optical products for frequency conversion applications. They can produce ultraviolet, noticeable, and near-infrared light from numerous laser resources, such as Nd: YAG, Ti: sapphire, and fibre lasers. BBO crystals have high nonlinear coefficients, a broad openness range, low group-velocity dispersion, and a high damage threshold. Creating top-notch BBO crystals requires cautious control of the crystal growth procedure and post-growth therapies.

This post will describe how we produce top-notch BBO crystals at our firm. We will also review some benefits and challenges of using BBO crystals for regularity conversion.

What is a BBO crystal?

BBO represents beta-barium borate (β-BaB2O4), a birefringent crystal with a trigonal framework. It belongs to the 3m point group with 3 major axes: X, Y, and Z. The Z-axis is parallel to the optical axis of the crystal as well as is likewise called the wonderful axis. The X- and Y-axes are perpendicular to the optical axis and are called regular axes.

BBO crystals have 2 refractive indices: ne for extraordinary rays and no for regular rays. The distinction between ne and also no depends on the wavelength of light as well as the temperature level of the crystal. This distinction creates phase inequality between various light polarization parts when propagating via a BBO crystal. Changing the angle between the light beam and the crystal axes can compensate for this stage inequality.

BBO crystals have significant nonlinear coefficients that permit effective regularity conversions processes such as second-harmonic generation (SHG), third-harmonic generation (THG), fourth-harmonic generation (FHG), fifth-harmonic generation (5HG), sum-frequency generation (SFG) and difference-frequency generation (DFG). These processes involve mixing 2 or more input beams of light with various regularities to generate an outcome beam of light with a new regularity.

Exactly how Do We Grow BBO Crystals?

We expand BBO crystals using a modified Czochralski method with a platinum crucible. The raw materials are barium carbonate (BaCO3) and boric acid (H3BO3), mixed in a stoichiometric ratio of 1:2. The mixture is then thawed at approximately 1100 ° C under an oxygen environment.

The seed crystal is a tiny BBO crystal with a well-defined orientation along one of its primary axes. The seed crystal is connected to a revolving pole that dips into the thaw surface area. The pole is gradually pulled up while turning at a constant speed. This triggers a thin melt layer to strengthen the seed crystal, developing a cylindrical boule.

The development rate relies on temperature slope, turning rate, pulling rate, thaw make-up, and oxygen pressure. We carefully check these factors throughout the growth process to ensure uniformity and quality of the boule.

The normal size of our boule is 50 mm in diameter and 100 mm in size. After expanding, we harden the boule at around 900 ° C for several hours to relieve internal tension and boost optical homogeneity.

Exactly how Do We Cut and also Gloss BBO Crystals?

We cut our boule into smaller pieces according to client requirements utilizing a diamond blade or wire saw maker. After that, polish these items using ruby powder or slurry on actors' iron or copper plates.

The reducing angle depends on the desired phase-matching condition for frequency conversion applications. Phase matching describes matching the stage velocities of different beams associated with nonlinear processes to ensure they add up constructively over cross countries inside the crystal.

There are two sorts of stage matching: critical stage matching (CPM) and noncritical phase matching (NCPM). CPM occurs when the input light beam circulates among the crystal's principal axes, such as the Z-axis. Its polarization is perpendicular to that axis, such as X- or Y-polarized. NCPM occurs when the input light beam circulates at an angle aside from zero or 90 levels worrying among the principal axes, such as the Z-axis. Its polarization is parallel to that axis, such as Z-polarized.

For CPM, we reduced our items at an angle equal to no or 90 levels concerning among the major axes. For NCPM, we cut our pieces at an angle determined by Snell's regulation:

ni sin( ɵi) = no sin( ɵo) where ni as well as no are the refractive indices of the input and also result from media, respectively, and ɵi and ɵo are the angles of incidence and refraction, respectively.

We polish our items using a fine-grained diamond powder or slurry on a cast iron or copper plate. We apply uniform pressure and motion to attain a smooth surface with low roughness and high flatness. We likewise layer our pieces with anti-reflection coatings to minimize reflection losses at the crystal surface areas.

The normal size of our pieces ranges from 1 mm to 25 mm in size or length. The surface area quality is far better than 10-5 scratch-dig according to the MIL-PRF-13830B standard. The surface flatness is better than lambda/8 at 633 nm wavelength. The parallelism is better than 10 arc secs. The clear aperture is larger than 90% of the main location.

What Are the Advantages of Using BBO Crystals?

BBO crystals have many advantages for frequency conversion applications, such as:

High nonlinear coefficients: BBO crystals have large nonlinear coefficients that allow effective regularity conversion processes with reduced input power needs. For example, BBO crystals have a nonlinear coefficient d31 of about 2 pm/V for SHG at 1064 nm wavelength, which is about 10 times larger than KDP crystals.

Broad transparency array: BBO crystals have a large openness variety from 189 nm to 3500 nm, covering ultraviolet, noticeable, and near-infrared areas. This enables BBO crystals to be used for numerous laser sources with various wavelengths.

Reduced group-velocity dispersion: BBO crystals have reduced group-velocity diffusion (GVD) that lessens the temporal broadening of ultrashort pulses throughout regularity conversion processes. For instance, BBO crystals have a GVD criterion β2 of concerning -35 fs ^ 2/mm for SHG at 800 nm wavelength, regarding two orders of size smaller sized than KDP crystals.

High damage limit: BBO crystals have high damage limits that endure high top and typical power without deterioration or damage. For example, BBO crystals have a damage threshold of 10 GW/cm ^ 2 for SHG at 1064 nm wavelength with 10 ns pulse duration, which is 5 times higher than KDP crystals.

What Are the Obstacles to Using BBO Crystals?

BBO crystals also have some difficulties for frequency conversion applications, such as:

Small approval angle: BBO crystals have a little acceptance angle that restricts the input beam of light's beam of light divergence and sets the top quality for reliable frequency conversion. For instance, BBO crystals have an approval angle of about 0.8 mrad-cm for SHG at 1064 nm wavelength, which has to do with four times smaller than that of KDP crystals.

Huge angular walk-off BBO crystals have a large angular walk-off that triggers spatial splitting between different polarization parts of light when circulating through a BBO crystal. This decreases the reliable communication length and also decreases the conversion efficiency. For instance, BBO crystals have an angular walk-off of about 38 mrad for SHG at 1064 nm wavelength, which has to do with six times larger than KDP crystals.

Temperature level sensitivity: BBO crystals' temperature sensitivity affects their refractive indices and phase-matching conditions. This requires temperature level stabilizing or tuning devices to maintain ideal efficiency. For instance, BBO crystals have a temperature bandwidth of 55 ° C-cm for SHG at 1064 nm wavelength, about 3 times smaller than KDP crystals.

Exactly how Do We Evaluate Our BBO Crystal Products?

 

We check our BBO crystal products by utilizing different techniques, such as:

X-ray diffraction (XRD): We use XRD to measure our boules and items' crystal structure and alignment. We ensure our items are pure beta-phase without alpha-phase contamination or twinning problems.

Optical transmission (OT): We utilize OT to measure the optical passage range of our items over their openness range. We ensure our products are without absorption bands or scattering losses because of impurities or issues.

Second harmonic generation (SHG): We utilize SHG to measure our items' nonlinear conversion performance and phase-matching angle for a given input wavelength. We ensure that our products satisfy the specs for SHG applications.

Third harmonic generation (THG): We use THG to measure our items' nonlinear conversion effectiveness and phase-matching angle for an offered input wavelength. We make sure that our products meet the specifications for THG applications.

Optical parametric oscillation (OPO): We use OPO to determine our items' nonlinear conversion efficiency and phase-matching angle for an offered input wavelength and signal/idler wavelengths. We make sure that our items meet the specifications for OPO applications.

Optical parametric amplification (OPA): We use OPA to gauge our items' nonlinear conversion effectiveness and phase-matching angle for an offered input wavelength and signal/idler wavelengths. We guarantee that our items satisfy the specs for OPA applications.

Optical parametric chirped-pulse amplification (OPCPA): We use OPCPA to determine our pieces' nonlinear conversion performance and phase-matching angle for an offered input wavelength and signal/idler wavelengths. We also determine the amplified pulses' temporal pulse shape and spectral transmission capacity. We make sure that our products fulfill the specs for OPCPA applications.

What Are Some Instances of BBO Crystal Applications?

BBO crystals have numerous applications in different fields, such as:

Laser science: BBO crystals are commonly utilized for frequency conversion procedures such as SHG, THG, OPO, OPA, and OPCPA to create ultraviolet, noticeable, or near-infrared light from different laser resources. For instance, BBO crystals can generate 266 nm light from 1064 nm Nd: YAG lasers or 400 nm light from 800 nm Ti: sapphire lasers.

Nonlinear optics: BBO crystals are additionally used for other nonlinear optical procedures such as sum-frequency generation (SFG), difference-frequency generation (DFG), optical rectification (OR), electro-optic modulation (EOM), as well as Pockels effect. For instance, BBO crystals can produce terahertz radiation from OR or modulate laser light beams with EOM.

Quantum optics: BBO crystals are useful for quantum optical experiments such as knotted photon set generation, quantum state tomography, quantum cryptography, and quantum width. For instance, BBO crystals can generate polarization-entangled photon sets from SPDC or carry out quantum interference dimensions with the Hong-Ou-Mandel impact.

How Can I Order Your BBO Crystal Products?

You can order our BBO crystal items by contacting us via e-mail or phone. You can also visit our internet site to search for our magazine and demand a quote online. We provide competitive rates as well as quick delivery worldwide. I appreciate your interest in our BBO crystal items!