Top Notch BBO Crystal Manufacturing

BBO crystals are among the most flexible nonlinear optical materials for frequency conversion applications. They can generate ultraviolet, visible, as well as near-infrared light from various laser resources, such as Nd: YAG, Ti: sapphire, and also fiber lasers. BBO crystals have high nonlinear coefficients, a wide openness array, reduced group-velocity dispersion, and a high damages threshold. However, creating top-quality BBO crystals requires cautious control of the crystal growth process and post-growth treatments.
This short article will certainly explain exactly how we create high-quality BBO crystals at our firm. We will additionally go over some advantages and also obstacles of using BBO crystals for frequency conversion.

What is a BBO crystal?

BBO means beta-barium borate (β-BaB2O4), a birefringent crystal with a trigonal framework. It comes from the 3m factor group with three principal axes: X, Y, as well as Z. The Z-axis is alongside the optical axis of the crystal and also is additionally called the terrific axis. The X- and Y-axes are perpendicular to the optical axis and are called ordinary axes.

BBO crystals have 2 refractive indices: ne for remarkable rays as well as no for normal rays. The distinction in between ne as well as no relies on the wavelength of light and the temperature level of the crystal. This distinction creates phase mismatch between various light polarization elements when circulating with a BBO crystal. Adjusting the angle in between the beam and also the crystal axes can compensate this phase inequality.

BBO crystals have big nonlinear coefficients that permit reliable frequency conversions processes such as second-harmonic generation (SHG), third-harmonic generation (THG), fourth-harmonic generation (FHG), fifth-harmonic generation (5HG), sum-frequency generation (SFG) as well as difference-frequency generation (DFG). These procedures include blending 2 or more input beam of lights with various frequencies to generate an outcome light beam with a new regularity.

How Do We Grow BBO Crystals?

We grow BBO crystals utilizing a modified Czochralski method with a platinum crucible. The raw materials are barium carbonate (BaCO3) as well as boric acid (H3BO3), blended in a stoichiometric proportion of 1:2. The mixture is then thawed at regarding 1100 ° C under an oxygen ambiance.

The seed crystal is a small BBO crystal with a distinct alignment along one of its primary axes. The seed crystal is affixed to a rotating rod that dips into the melt surface. The rod is gradually brought up while revolving at a constant speed. This triggers a slim thaw layer to solidify on the seed crystal, forming a cylindrical boule.

The development price relies on temperature gradient, turning rate, drawing speed, melt make-up, and also oxygen pressure. We very carefully keep track of these elements throughout the development process to ensure uniformity and also top quality of the boule.

The common size of our boule is about 50 mm in diameter and 100 mm in length. After growing, we harden the boule at about 900 ° C for numerous hours to relieve interior stress and also boost optical homogeneity.

How Do We Cut and Polish BBO Crystals?

We reduced our boule into smaller sized pieces according to client requirements using a diamond blade, or cord saw machine. After that brighten these pieces utilizing diamond powder or slurry on actors' iron or copper plates.

The reducing angle relies on the preferred phase-matching condition for frequency conversion applications. Stage matching refers to matching the stage speeds of various beams involved in nonlinear processes to ensure that they add up constructively over cross countries inside the crystal.

There are two sorts of phase matching: essential phase matching (CPM) and also noncritical stage matching (NCPM). CPM takes place when the input beam of light circulates along among the primary axes of the crystal, such as the Z-axis, as well as its polarization is perpendicular to that axis, such as X- or Y-polarized. NCPM occurs when the input beam propagates at an angle besides absolutely no or 90 levels concerning among the primary axes, such as the Z-axis. Its polarization is alongside that axis, such as Z-polarized.

For CPM, we reduced our pieces at an angle equal to no or 90 levels worrying among the primary axes. For NCPM, we reduced our pieces at an angle identified by Snell's legislation:

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

We brighten our items utilizing a fine-grained ruby powder or slurry on an actors iron or copper plate. We use uniform stress as well as movement to accomplish a smooth surface area with reduced roughness and also high flatness. We also layer our pieces with anti-reflection finishes to minimize representation losses at the crystal surfaces.

The regular dimension of our items ranges from 1 mm to 25 mm in size or length. The surface top quality is better than 10-5 scratch-dig according to the MIL-PRF-13830B criterion. The surface flatness is far better than lambda/8 at 633 nm wavelength. The parallelism is much better than 10 arc seconds. The clear aperture is larger than 90% of the central area.

What Are the Advantages of Using BBO Crystals?

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

· High nonlinear coefficients:

BBO crystals have huge nonlinear coefficients that make it possible for efficient regularity conversion processes with reduced input power needs. For example, BBO crystals have a nonlinear coefficient d31 of concerning 2 pm/V for SHG at 1064 nm wavelength, which has to do with 10 times larger than KDP crystals.

· Broad openness variety:

BBO crystals have a broad openness array from 189 nm to 3500 nm, covering ultraviolet, visible, as well as near-infrared areas. This permits BBO crystals to be made use of for different laser resources with various wavelengths.

· Reduced group-velocity dispersion:

BBO crystals have reduced group-velocity dispersion (GVD) that lessens the temporal broadening of ultrashort pulses during frequency conversion processes. As an example, BBO crystals have a GVD parameter β2 of about -35 fs ^ 2/mm for SHG at 800 nm wavelength, concerning two orders of size smaller sized than KDP crystals.

· High damages limit:

BBO crystals have high damage limits that can endure high top and ordinary power without deterioration or damage. As an example, BBO crystals have a damage threshold of about 10 GW/cm ^ 2 for SHG at 1064 nm wavelength with 10 ns pulse duration, about five times greater than KDP crystals.

What Are the Obstacles to Using BBO Crystals?

BBO crystals additionally have some challenges for regularity conversion applications, such as:

· Tiny acceptance angle:

BBO crystals have a small acceptance angle that limits the input beam of light's beam divergence and also sets top quality for effective frequency conversion. As an example, BBO crystals have an acceptance angle of regarding 0.8 mrad-cm for SHG at 1064 nm wavelength, which has to do with four times smaller than that of KDP crystals.

· Big angular walk-off :

BBO crystals have a big angular walk-off that creates spatial splitting up between different polarization elements of light when circulating with a BBO crystal. This reduces the reliable communication length as well as decreases the conversion performance. For example, 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 of sensitivity:

BBO crystals' temperature level of sensitivity influences their refractive indices and also phase-matching problems. This needs temperature level stabilization or tuning tools to keep optimal performance. For example, BBO crystals have a temperature level transmission capacity of concerning 55 ° C-cm for SHG at 1064 nm wavelength, regarding three times smaller sized than KDP crystals.

Just How Do We Check Our BBO Crystal Products?

We test our BBO crystal products by utilizing numerous techniques, such as:

· X-ray diffraction (XRD):

We utilize XRD to gauge our boules and items' crystal framework as well as alignment. We make certain that our items are pure beta-phase without alpha-phase contamination or twinning flaws.

· Optical transmission (OT):

We utilize OT to determine the optical transmittance spectrum of our pieces over their transparency array. We guarantee our products are free from absorption bands or scattering losses due to pollutants or problems.

· Second harmonic generation (SHG):

We use SHG to measure our items' nonlinear conversion effectiveness as well as phase-matching angle for a given input wavelength. We make certain that our products meet the specs for SHG applications.

· Third harmonic generation (THG):

We utilize THG to measure our items' nonlinear conversion efficiency and phase-matching angle for an offered input wavelength. We guarantee that our products fulfill the specifications for THG applications.

· Optical parametric oscillation (OPO):

We utilize OPO to gauge our items' nonlinear conversion performance and phase-matching angle for a provided input wavelength and signal/idler wavelengths. We guarantee that our products satisfy the specifications for OPO applications.

· Optical parametric amplification (OPA):

We use OPA to measure our pieces' nonlinear conversion efficiency as well as phase-matching angle for a provided input wavelength and also signal/idler wavelengths. We make sure that our products satisfy the specifications for OPA applications.

· Optical parametric chirped-pulse amplification (OPCPA):

We make use of OPCPA to gauge our items' nonlinear conversion effectiveness as well as phase-matching angle for a provided input wavelength and also signal/idler wavelengths. We likewise determine the magnified pulses' temporal pulse shape as well as spectral transmission capacity. We make sure that our products satisfy the requirements for OPCPA applications.
What Are Some Examples of BBO Crystal Applications?

BBO crystals have many applications in different areas, such as:

· Laser scientific research:

BBO crystals are extensively made use of for regularity conversion procedures such as SHG, THG, OPO, OPA, as well as OPCPA to generate ultraviolet, visible, or near-infrared light from different laser sources. As an example, 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 made use of for other nonlinear optical procedures such as sum-frequency generation (SFG), difference-frequency generation (DFG), optical rectification (OR), electro-optic modulation (EOM), and also Pockels effect. As an example, BBO crystals can produce terahertz radiation from OR or modulate laser beam of lights with EOM.

· Quantum optics:

BBO crystals are useful for quantum optical experiments such as entangled photon set generation, quantum state tomography, quantum cryptography, and also quantum assessment. For example, BBO crystals can generate polarization-entangled photon sets from SPDC or perform quantum interference dimensions with the Hong-Ou-Mandel effect.

Just How Can I Order Your BBO Crystal Products?

You can order our BBO crystal items by calling us with e-mail or phone. You can additionally visit our site to surf our directory and also demand a quote online. We provide competitive costs as well as fast distribution worldwide. I appreciate your interest in our BBO crystal items!

https://www.laser-crylink.com/laser-products/nonlinear-crystal/bbo-crystal/