Effect of low dose high energy O3+ implantation on refractive index and linear electro-optic properties in X-cut LiNbO3: Planar optical waveguide formation and characterization

Abstract

X-cut LiNbO3 crystals were implanted at room temperature by 5.0 MeV O3+ ions with doses ranging from 1.0×1014 to 6.0×1014 O/cm2. Secondary ion mass spectrometry profiles of atomic species migration as well as damage profiles by the Rutherford backscattering channeling technique and refractive index variation were investigated as a function of dose and subsequent annealing conditions. Two different kinds of damage produced by oxygen implantation were seen: near-surface damage correlated to electronic stopping, which causes an increase of the extraordinary refractive index, and end-of-ion range damage generated by collision cascades, which decreases the extraordinary refractive index values. The different nature of the two kinds of damage is also seen by the different temperature conditions needed for recovery. Low loss planar optical waveguides were obtained and characterized by the prism coupling technique.

Femtosecond laser and swift-ion damage in lithium niobate: A comparative analysis

“…The amorphous fraction has been assessed by RBS/C channeling experiments. 7,33 One sees that in the cases of O and F, a certain prior or incubation fluence ⌽ is required to start full amorphization in comparison with Si ͑7.5 MeV/nm͒ where it starts at a much smaller fluence ͑in this case, ⌽ = ⌽ 0 is the overlapping fluence͒. The occurrence of an incubation fluence is also inferred from optical ͑dark-mode͒ data obtained for higher fluences, where a full homogeneous amorphous layer is induced.…”

“…[8][9][10] Light from a He-Ne laser ͑633 nm͒ of 5 mW power was coupled into the sample through a standard isosceles rutile prism. Also, the areal fraction of disorder has been obtained through Rutherford backscattering spectrometry [7][8][9][10] under channeling conditions ͑RBS/C͒. Spectra were generally taken along the c trigonal axis using either 2-3 MeV protons or He ions.…”

“…On the other hand, irradiation of dielectric solids with swift ions, i.e., operating in the electronic stopping power regime, are being progressively used as an alternative to nuclear collision damage and implantation 6 to induce structural modifications [7][8][9] and produce devices, e.g., for optoelectronics and photonics. 7,[10][11][12][13] In such electronic regime, individual ions generate amorphous ͑latent͒ tracks of only a few nanometers in diameter [14][15][16] when the electronic stopping power overcomes a certain threshold value, which depends on material and, at a lesser extent, on irradiation conditions.…”

“…7,[10][11][12][13] In such electronic regime, individual ions generate amorphous ͑latent͒ tracks of only a few nanometers in diameter [14][15][16] when the electronic stopping power overcomes a certain threshold value, which depends on material and, at a lesser extent, on irradiation conditions. This technique opens new possibilities for nanostructuring of materials and may compete with femtosecond-laser pulse irradiation.…”

“…Therefore, the purpose of this work is to present experimental observations of a number of relevant phenomenological features and explore whether a correlation between laser and ion damage can be reasonably established. We will specifically focus on a relevant photonic material, 18 LiNbO 3 ͑having a gap of around 4 eV͒, where some systematic information on the effect of femtosecond laser [19][20][21][22] and swift-ion irradiation [7][8][9][10][11][12][13][23][24][25] ready available. To the best of our knowledge, only a few systematic comparisons have so far been reported.…”