Laser Damage Threshold Measurements Research Articles

Study on the Duration of Laser-Induced Thin Film Plasma Flash

The accuracy of judging whether the film is damaged directly affects the accuracy of the measurement of the film laser damage threshold. When judging the film damage by the traditional plasma flash method, there is a problem of misjudgment caused by the failure to distinguish the film and air plasma flash. In order to eliminate misjudgment, the two flashes are accurately distinguished by the difference in the duration of the air and film plasma flash. This paper aims to obtain the theoretical and experimental values of the duration of the film plasma flash (tf) and analyze the factors affecting it. Firstly, taking single-layer hafnium oxide and aluminum oxide thin films as examples, when the wavelength of the incident laser is 1064 nm, the diameter of the laser focusing spot is 0.08 cm, the energy of the incident laser is 100 mJ, and the pulse width of incident laser is 10 ns, the tf of hafnium oxide, and aluminum oxide thin films are 542.7 and 299.6 ns, respectively. Secondly, the experimental study of tf was carried out. Through six experiments, the following results were obtained: (1) With the increase in incident laser energy, the tf of both films increases; (2) The tf of the hafnium oxide film is longer than that of the aluminum oxide film. (3) The experimental parameters are put into the calculation model, and the theoretical results are in good agreement with the experimental tf values. Finally, it is found that tf increases with the increase in incident laser energy and incident laser pulse width, and decreases with the increase in focusing spot diameter.

Cd3(IO3)(IO4)F2·0.1CdO: A Nonlinear-Optical Crystal with the Introduction of Fluoride into Iodate Containing Both [IO3]- and [IO4]3- Groups.

A new d10 transition-metal iodate fluoride, namely, Cd3(IO3)(IO4)F2·0.1CdO, was successfully designed and synthesized via the mid-infrared hydrothermal method. It crystallizes in the polar space group R3m and features the coexistence of the [IO3]- and [IO4]3- groups. Cd3(IO3)(IO4)F2·0.1CdO has a strong second-harmonic-generation response of about 3.0 times that of KDP(KH2PO4), large birefringence (0.133 at 546.1 nm), and a wide energy band gap (4.00 eV). In addition, the power laser damage threshold (LDT) measurement indicated that it possesses a high LDT of 84.29 MW/cm2, which is about 30 times that of AgGaS2. These superior properties showed that Cd3(IO3)(IO4)F2·0.1CdO may be an excellent nonlinear-optical crystal for visible and mid-infrared application.

Linear‐Nonlinear Optical and Quantum Chemical Studies on Quinolinium 4‐Aminobenzoate: A Third Order Non‐Linear Optical Material for Optoelectronic Applications

AbstractGood quality single crystals of a non‐linear optical (NLO) material, quinolinium 4‐aminobenzoate (ABAQ), are grown by employing solution growth technique. The crystal structure is confirmed via single crystal X‐ray diffraction studies. Grown crystals of the ABAQ compound are characterized by powder X‐ray diffraction, Fourier transform infrared, thermal analysis, and mechanical studies. Ultraviolet–vis–near infrared (UV–vis–NIR) and photoluminescence spectra reflect the optical transmission range of the obtained compound. Dielectric studies and laser damage threshold measurement are carried out to verify the non‐linear activity and surface resistance of the grown crystal. From the Kurtz Perry powder technique, the second harmonic generation efficiency of the ABAQ compound is estimated to be 90% that of the standard potassium dihydrogen phosphate. Z‐Scan technique is performed to investigate the non‐linear behavior of ABAQ crystal. The suitability of ABAQ material for optical limiting and switching applications is also verified. Computational analysis performed upon the stable geometry of ABAQ molecule using density functional theory strongly supports the experimental findings with a significant chemical background. The non‐linear behavior of the title compound is determined by investigating various non‐linear optical (NLO) parameters of electric dipole moment, polarizability, and hyperpolarizability. Based on these inferences, the ABAQ material can be declared as a promising material for optical limiting and switching applications in optoelectronics regime.

Linear–nonlinear optical and quantum chemical studies on Quinolinium 3,5-dinitrobenzoate: A novel third order non-linear optical material for optoelectronic applications

An organic non-linear optical (NLO) crystal of Quinolinium 3,5-dinitrobenzoate (DNBAQ) was synthesized and good quality single crystals of DNBAQ were grown by conventional slow evaporation solution growth technique. Single crystal XRD was utilized to confirm the formation of the charge transfer complex. The crystalline property and the presence of required functional groups was verified employing Powder XRD and FTIR spectral analysis. UV–Vis–NIR and Fluorescence study was performed to determine the optical transmittance and the emission property of the grown crystal. The thermal, mechanical and surface damage threshold stability of the complex was analysed using thermal studies, Vicker’s micro hardness studies and Laser damage threshold measurement. The solid state parameter of electronic polarizability of DNBAQ compound was computed through dielectric studies. The non-linear optical characterizations like Kurtz Perry powder technique and Z-Scan technique ensures the non-linear optical activity of the compound. The frequency conversion efficiency of the grown crystal was estimated to be 70% that of the standard Potassium Dihydrogen Phosphate (KDP). Z-Scan analysis confirms the suitability of the grown crystal for optical limiting and switching applications. Quantum chemical studies were adopted on the optimized geometry of DNBAQ molecule using Density Functional Theory (DFT). Frontier Molecular Orbital (FMO) analysis and Molecular Electrostatic Potential (MEP) analysis were performed. The non-linear optical behaviour of the complex was established by evaluating dipole moment, polarizability and hyperpolarizability features. All the above results confirm the resourceful candidature of DNBAQ material for optoelectronic and photonic applications.

Synthesis, growth, structure, spectroscopic, and physicochemical properties of 18-Crown-6-ether barium (II) bisthiocyanate monohydrate single crystal: BCBT

We reported the bulk size with a dimension of 18×5×5 mm3 single-crystals of 18C6(Ba)(SCN)2.H2O [18-crown-6-ether barium(II) bisthiocyanate monohydrate]; abbreviated as BCBT, have been grown from an aqueous solution via slow evaporation solvent technique(SEST). The grown pristine single-crystals have characterized by single crystal X-ray diffraction (XRD), FT-IR, micro-Raman, and UV-Vis-NIR spectral studies. BCBT crystallizes in a monoclinic with a non-centrosymeetric space group of P21 crystal system. Additionally, the chemical etching studies showed that the reverse crystal growth rates of BCBT. The FT-IR studies confirmed the present of functional groups in the grown single-crystal of BCBT. Interestingly, the CN stretching observed at 2012 cm−1 is clearly shown the N-bonded nature of SCN with Ba2+. Moreover, the micro-Raman spectrum is used to further additional confirmation of BCBT single-crystal. In the entire visible region, the BCBT crystal has found to be wide (UV-Vis-IR) optically absorption from 231 to 800 nm, which is suitable for optoelectronic applications. The laser damage threshold measurements on the BCBT crystal with Q-switched Nd: YAG laser of fundamental wavelength 1064 nm (QUANTA RAY Model LAB – 170 - 10, pulse width 10 ns and repetition rate 6 Hz used as the source of light for laser damage threshold experiment. Moreover, the thermal stability of grown BCBT is stable up to 289 °C. From the results reveal that the sample possess admirable thermal stability compared to other IOPS series such as CLTC (171°C), and ACCTC (241°C).

Growth, linear- nonlinear optical studies and quantum chemistry formalism on an organic NLO crystal for opto-electronic applications: experimental and theoretical approach

An organic non-linear optical material of 4-methylanilinium 3,5-dinitrobenzoate (MADNBA) was synthesized and crystals of MADNBA were grown by employing slow evaporation solution growth technique. The crystal structure was confirmed from Single crystal XRD. Grown crystals were characterized by Powder XRD, UV–Vis–NIR, Photoluminescence and Laser damage threshold measurement studies. Infrared spectroscopy, thermal analysis and microhardness measurement were performed to study the molecular vibration, thermal behaviour and mechanical stability of the grown crystal. Dielectric studies have been performed to evaluate various solid state parameters. From the Kurtz Perry powder technique, it was found that Second harmonic generation efficiency of the obtained compound is 10 times that of the standard potassium dihydrogen phosphate. Z-Scan technique was also carried out to investigate the non-linear activity and optical limiting behaviour of MADNBA crystal. Computational analysis performed upon the optimized geometry of MADNBA molecule using Density Functional Theory confirmed the experimentally determined quantities under a strong theoretical background. Frontier molecular orbital analysis and molecular electrostatic potential analysis were carried out. The non-linear character of the compound was also determined by computing various non-linear optical parameters like dipole moment, polarizability and hyperpolarizability. The first order hyperpolarizability (β) value of the MADNBA molecule was evaluated to be 8 times that of the standard urea molecule. Based on these results, it could be proposed that MADNBA material serves as a potential candidate for frequency doubling, optical limiting and photonic applications in optoelectronics domain.

A Survey of Transparent Conducting Films and Optoelectrical Materials for High Optical Power Applications

The lifetime laser damage performance of a wide range of transparent conductive materials is assessed, including ultrathin metal films, doped metal oxides, doped compound semiconductors, and graphene whose carrier densities span five orders of magnitude from 1018 to 1023 cm−3. Lifetime laser damage thresholds are determined by exposing material surfaces to repeated nanosecond laser pulses at near IR wavelengths (1064 nm). Near threshold fluences, two distinct damage modes, i.e., bulk and discrete, emerge depending on carrier density. These bulk and discrete damage modes are attributed to free carrier‐induced bulk and localized, defect‐driven absorption processes, respectively. For polycrystalline films with free carrier densities greater than ≈1020 cm−3, laser damage thresholds are less than 5 J cm−2. In contrast, bulk absorption is not apparent at thresholds substantially higher than ≈10 J cm−2 in single‐crystal films with free carrier concentrations lower than ≈1019 cm−3. By increasing thickness, films with lower carrier densities can deliver relevant levels of sheet conductance (<200 Ω sq−1) while remaining transparent. These lifetime laser damage threshold measurements offer systematic criteria to select materials aimed at handling high optical powers in optoelectronics devices and emerging plasmonic and metamaterials for lasers.

Synthesis, growth and physicochemical properties of new organic nonlinear optical crystal l-threoninium tartrate (LTT) for frequency conversion

An organic nonlinear optical l-threoninium tartrate (LTT) single crystal was successfully grown by slow evaporation method using de-ionized water as solvent. The orthorhombic structure and non-centrosymmetric space group of P2221 of the grown LTT crystal was confirmed using single crystal X-ray diffraction analysis. The various functional groups and bonding nature of the LTT crystal were realized using FT-IR spectroscopic analysis. The linear optical behavior is examined using UV–Visible spectroscopy revealing the absences of absorbance in the wavelength region of 230–1100 nm. Tauc’s relation is employed to obtain the optical band gap and it is found to be 6.4 eV. The optical parameters like extinction coefficient (K), reflectance (R) and refractive index (n0) are also calculated for the grown LTT crystal. With respect to the frequency and temperature the dielectric constant and dielectric loss were estimated. The Vickers hardness number (Hv), Meyer’s index (n), yield strength (σr), elastic constant (C11), fracture toughness (KC) and Brittle index number (Bi) were calculated using the micro-indentation test. Thermo-gravimetric (TG) and differential thermal (DT) analysis confirm the single stage decomposition and 257 °C melting point of the titular crystal. The exact melting point of the crystal is found to be 268 °C using auto melting point apparatus. The layer growth with 2D nucleation mechanism and less dislocation is confirmed by chemical etching analysis. The surface quality of the titular crystal was studied using laser damage threshold (LDT) measurement and it is found to be 6.57 GW/cm2. Kurtz and Perry method was employed to estimate the second harmonic generation efficiency of the titular crystal and is found to be 2.91 times greater than the KDP crystal. The χ(3), n2 and β of the titular crystal was estimated using Z-scan technique and they are found to be 7.1368 × 10−10 (esu), 0.8466 × 10−12 (cm2W−1) and 3.734 × 10−6 (cmW−1) respectively. Reverse saturable absorption observed in open aperture Z-scan indicates the suitability of titular crystal for optical limiting application.

HBa2.5(IO3)6(I2O5) and HBa(IO3)(I4O11): Explorations of Second-Order Nonlinear Optical Materials in the Alkali-Earth Polyiodate System.

Two new barium polyiodate compounds in the alkali-earth system, namely, HBa2.5(IO3)6(I2O5) ( Fdd2) and HBa(IO3)(I4O11) ( P1̅) have been obtained through hydrothermal reaction. Interestingly, the structures of both compounds feature different polyiodate groups, i.e., I2O5 and I4O11 groups. HBa2.5(IO3)6(I2O5) can be depicted as an alternative stacking of two-dimensional (2D) [Ba4(IO3)8(I2O5)2] and [Ba(IO3)4(I2O5)2]2- layers with the I2O5 and IO3 group serving as linkers. HBa(IO3)(I4O11) can be depicted as a 3D network with 2D [Ba(I4O11)] layers being interconnected by IO3 groups. The 0D I4O11 polyiodate group can be seen also viewed as formed by an I3O8 group further corner-sharing with an IO3 group or an I2O5 group further corner-sharing with two IO3 groups. Powder second harmonic generation (SHG) measurements show that HBa2.5(IO3)6(I2O5) crystals display a moderate SHG efficiency of ∼1.6 times that of KH2PO4 (KDP) and are phase-matchable. Optical properties measurements, thermal analyses, and laser damage threshold (LDT) measurements have been performed. Results of theoretical calculation show that the formation of I4O112- is thermodynamically much easier than I3O8- and I2O5, because of the lower reaction energy. Our studies shed light on exploring alkali-earth polyiodates as potential NLO materials.

Investigations on 4-methyl benzophenone (4MB) single crystal grown by Czochralski method and its characterization

Bulk size 4-methyl benzophenone (4MB) single crystals have been grown by Czochralski method in a period of 8 h. The unit cell parameters of the grown crystals were confirmed by single crystal X-ray diffraction analysis. The lower UV cut-off wavelength of 4MB crystal was studied by UV–Vis NIR spectrum analysis and the cut-off wavelength was found to be 379 nm. The FTIR spectrum confirms the presence of different functional groups present in the crystal. The luminescence properties of 4MB single crystal were described by Photoluminescence spectra. Thermal stability, material decomposition and melting point of the grown crystals were determined by Thermogravimetric/differential thermal analysis measurements. The mechanical stability of the 4MB single crystal was examined using Vickers microhardness test and it was found that the crystal belongs to soft material category. Laser damage threshold measurement was carried out by using Nd:YAG laser. The nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear susceptibility were measured from Z-Scan measurements. The density functional theory calculations for isolated 4MB molecule were performed with B3LYP/6-311 + + G(d,p) level. The electronic properties and polarizabilities of title molecule were calculated.

Crystal growth and characterization of an efficient semi-organic nonlinear optical (NLO) donor-π-acceptor single crystal: 2-amino-5-nitropyridinium nitrate (2A5NPN) grown by slow evaporation solution technique (SEST)

The semi-organic nonlinear optical 2-amino-5-nitropyridinium nitrate (2A5NPN) single crystals were successfully grown by slow evaporation solution technique with the dimension of 10 × 10 × 10 mm3. The crystalline structure of 2A5NPN was confirmed by single crystal X-ray diffraction measurement. The optical quality of the grown crystal was studied using UV–Vis–NIR spectrum analysis. It shows that the grown crystal has 69% of transmittance with the lower cut-off wavelength of 404 nm. The refractive index of 2A5NPN single crystal was calculated using the Prism-coupling method. The thermal diffusivity was analyzed using photoacoustic measurement. The dark and photoconductivity of the grown crystal were analyzed and the result shows that the crystal has negative photoconductivity nature. The mechanical strength of 2A5NPN crystal was analyzed by Vickers microhardness tester and the hardness number ( $${H_v}$$ ), Meyer’s index (n), yield strength (σy), stiffness constant (C11) and Hays–Kendall relation were evaluated. The fundamental solid state parameters such as valence electron plasma energy (ћωp), Penn gap (Ep), Fermi energy (Ef) and various type of electronic polarizability (α) of the grown crystal were determined using the dielectric parameters. The HOMO–LUMO energy and first-order hyperpolarizability (β) of 2A5NPN molecule were calculated in the gas phase by density functional theory. The laser damage threshold measurement has been performed and it reveals that the optical damage tolerance power of the grown crystal is high compared to other organic and inorganic NLO crystals. The third-order nonlinearity of 2A5NPN was assessed using an open and closed aperture Z-scan technique. The above results show that 2A5NPN crystal is a potential candidate for nonlinear optical device applications.

Bulk growth of organic 4-hydroxy l-proline (HLP) single crystals grown by conventional slow evaporation and Sankaranarayanan–Ramasamy (SR) method

Organic single crystals of 4-hydroxy l-proline (HLP) were grown by conventional slow evaporation and Sankaranarayanan–Ramasamy (SR) method in an aqueous medium. With a vision to improve the crystal quality, SR method was adopted and optically transparent HLP single crystal, (110) directed, with the size of 80 mm length and 15 mm diameter was grown. The crystalline structure of the grown crystal was analyzed by single crystal X-ray diffraction (SXRD) analysis. The conventional and SR method grown HLP crystals were characterized and the results were compared by UV–Vis–NIR, photoluminescence, chemical etching, Vickers microhardness, dielectric permittivity, dielectric loss, photoconductivity, photoacoustic, laser damage threshold (LDT) and second harmonic generation (SHG) measurements. The thermal property of the grown crystal was carried out by thermogravimetric (TG) and differential thermal analysis (DTA). The SHG efficiency of HLP crystal was determined using Kurtz–Perry powder technique. The comparative optical transmittance study clearly indicates that the transmission of SR method grown HLP crystal is 10% higher and quite good in the entire visible and near infrared region which suggest its suitability for optical device applications. The distribution of structural defects and the etch pit density (EPD) of the grown crystals were determined by chemical etching analysis. The Vickers microhardness measurement reveals that the hardness of SR method grown HLP crystal is higher compared to conventional method grown crystal. The dielectrics, photoconductivity, photoacoustic and laser damage threshold studies clearly indicate that the crystal grown by SR method possesses good quality compared to conventional method grown crystal.

Investigations on nucleation, HRXRD, optical, piezoelectric, polarizability and Z-scan analysis of l–arginine maleate dihydrate single crystals

An efficient organic nonlinear optical single crystal of l-arginine maleate dihydrate (LAMD) has been grown by slow evaporation solution technique (SEST) and slow cooling technique (SCT). The crystalline perfection of the crystal was examined using high–resolution X–ray diffractometry (HRXRD) analysis. Photoluminescence study confirmed the optical properties and defects level in the crystal lattice. Electromechanical behaviour was observed using piezoelectric co-efficient (d33) analysis. The photoconductivity analysis confirmed the negative photoconducting nature of the material. The dielectric constant and loss were measured as a function of frequency with varying temperature and vice-versa. The laser damage threshold (LDT) measurement was carried out using Nd:YAG Laser with a wavelength of 1064 nm (Focal length is 35 cm) and the obtained results showed that LDT value of the crystal is high compared to KDP crystal. The high laser damage threshold of the grown crystal makes it a potential candidate for second and higher order nonlinear optical device application. The third order nonlinear optical parameters of LAMD crystal is determined by open-aperture and closed-aperture studies using Z-scan technique. The third order linear and nonlinear optical parameters such as the nonlinear refractive index (n2), two photon absorption coefficient (β), Real part (Reχ3) and imaginary part (Imχ3) of third-order nonlinear optical susceptibility are calculated.

Comprehensive study on l-Proline Lithium Chloride Monohydrate single crystal: A semiorganic material for nonlinear optical applications

l-Proline Lithium Chloride Monohydrate single crystal has been successfully synthesized and grown by slow evaporation solution technique. The lattice dimensions have been calculated by single crystal XRD. The presence of strain inside the crystal has been evaluated by powder X-ray diffraction. Its crystalline perfection was found to be good with the full width at half maxima of 29.31arc sec. The crystal quality can be further examined by time resolve photoluminescence spectroscopy. The dielectric constant and dielectric loss have been measured over the frequency range of 10Hz–10kHz. The curve plotted during the measurement suggests that the value of dielectric constant decreases at higher frequency which ensures that the crystal is good candidate for NLO devices. The laser damage threshold measurements have been performed for single and multiple shots which reveal that the tolerance power for the single shot is more as compared to multiple shots. Its third order nonlinearity and thermal parameters have also been assessed for the title compound. The interference patterns obtained from the birefringence studies infer the optical homogeneity and defects in the grown crystals. The density of the single crystal has been calculated by floating technique taking kerosene as a reference.

The role of electronic defects and brittle microstructure in laser-driven material failure

The microstructural thermal response of fused silica subjected to laser-induced breakdown was investigated. Rapid thermal annealing of laser modified material at the surface was achieved using a CO2 laser and the relaxation response of photoluminescence, infrared (IR) reflectance, electron and white light microscope images were recorded. Subsequent nanosecond-pulsed laser damage threshold measurements revealed thermally driven kinetics which were dominated by absorbing defect annealing at heat-treatment temperatures (THT) below ∼1200 K and material toughening at higher THT. A decrease in the peak photoluminescence lifetime with THT revealed two types of defects which were correlated with non-bridging IR vibrational modes. Near the glass transition temperature, a weakening of the laser modified material was observed and explained in terms of a residual compressive stress relaxation. A nonlinear absorption model was used to predict optical breakdown threshold and compared with critical fracture predictions based on crack tip annealing. Combined with a qualitative stress relaxation analysis, our model agrees well with the experimental data and yields insight to the rate-limiting contributions driving the onset of laser-induced breakdown in defective silica.

Laser-induced damage thresholds of bulk and coating optical materials at 1030 nm, 500 fs

We report on extensive femtosecond laser damage threshold measurements of optical materials in both bulk and thin-film form. This study, which is based on published and new data, involved simple oxide and fluoride films, composite films made from a mixture of two dielectric materials, metallic films, and the surfaces of various bulk materials: oxides, fluorides, semiconductors, and ionic crystals. The samples were tested in comparable conditions at 1030 nm, 375 to 600 fs, under single-pulse irradiation. A large number of different samples prepared by different deposition techniques have been tested, involving classical materials used in the fabrication of optical thin film components (Ag, AlF3, Al2O3, HfO2, MgF2, Nb2O5, Pt, Sc2O3, SiO2, Ta2O5, Y2O3, and ZrO2) and their combination with codeposition processes. Their behaviors are compared with the surfaces of bulk materials (Al2O3, BaF2, CaF2, Ge, KBr, LiF, MgF2, NaCl, Quartz, Si, ZnS, ZnSe, and different silica glasses). Tabulated values of results are presented and discussed.

Fluence uncertainties of laser damage threshold measurements

The laser-induced damage threshold (LIDT) determines how optical components are used in a high power laser system, and its uncertainty is key for making comparisons between different LIDT measurements. In this work, we present an analysis of fluence uncertainties of LIDT measurements. The corresponding mathematical expressions for the fluence uncertainties have been established to deal with the statistical data obtained from a one-on-one damage experiment. The results show that the uncertainties are mainly caused by the measurement and calculation of the laser fluence and the damage probability at each fluence level, and the linear fit in a plot of laser fluence versus damage probability.

Growth and characterization of Cu (II) doped negatively soluble lithium sulfate monohydrate crystals

Single crystals of pure and Cu (II) doped negatively soluble lithium sulfate monohydrate have been grown by slow evaporation solution technique. In the present work, to improve the crystalline quality of lithium sulfate monohydrate crystal, metal dopant was incorporated into the pure crystals. The as grown crystals are clear, transparent and the sizes of the crystals were up to 18×12×3mm3 and 50×15×5mm3. The presence of metal dopant has been confirmed by energy dispersive spectroscopy, atomic absorption spectroscopy analysis. Single crystal and powder X-ray diffraction studies were carried out to ascertain lattice parameters and identify different phase nature. Optical transmission spectrum of the grown crystals was recorded. FT-IR and thermal analysis were carried out to investigate the functional group and thermal behavior of the grown crystals respectively. The grown crystal was subjected to Vickers micro hardness, HRXRD, piezoelectric, laser damage threshold measurements and second harmonic generation efficiency studies.

1 064nm高反射薄膜激光损伤阈值测量方法

1 064nm高反射薄膜激光损伤阈值测量方法

Optical, structural and microhardness properties of KDP crystals grown from urea-doped solutions

Potassium dihydrophosphate single crystals were grown from aqueous solutions onto a point seed using temperature reduction method by doping with different molar values of urea. The characterization of the grown crystals was made by visible and Fourier transform infrared spectroscopy, Vicker's hardness studies, X-ray powder diffraction, non-linear optical and laser damage threshold measurements. By comparing these crystals with the ones grown from the pure solution, it is shown that 0.2–2.0M of the urea additive enhances the laser damage threshold and the second harmonic efficiency more than by 25 and 20%, respectively. By means of the Bond method using a multipurpose three-crystal X-ray diffractometer it is shown that the presence of urea additive increases the crystal lattice parameter c of the grown crystals, whereas the lattice parameter a is by an order less sensitive to the changing urea concentration in the solution. The Vicker's hardness studies at room temperature carried out on (100) and (001) crystallographic planes show an increased hardness of the doped crystals (grown in the presence of urea additive) on the plane (001) in comparison with that of pure potassium dihydrophosphate crystal.