Optical properties of reduced LiNbO<sub>3</sub>

Jhans, H.; Honig, J. M.; Rao, C. N. R.

doi:10.1088/0022-3719/19/19/019

Cited by 34 publications

(17 citation statements)

References 45 publications

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“…This band has been previously detected for LN annealed in O 2 -free atmospheres. The origin of this peak has been the subject of controversy as reported by Jhans et al 16 since it has been ascribed to polarons, or d-d transitions of niobium or to electrons trapped at oxygen vacancies originated during the surface decomposition or to cation and oxygen vacancies. 17…”

Section: Vacuum Outgassing Effect On the Surface Of Lithium Niobatementioning

confidence: 96%

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

Lee¹,

Namkoong²,

Doolittle³

et al. 2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The characteristics and growth of III-nitride materials on ferroelectric lithium niobate with varying Li mole composition have been investigated to achieve a better device performance of AlGaN∕GaN heterojunction structures. III-nitride growth on lithium niobate has been performed after high temperature (1000°C) furnace thermal treatments in dry air environment resulting in atomically flat surfaces on lithium niobate (LN). However, while this furnace thermal treatment results in improved surface smoothness and III-nitride adhesion, it also causes repolarization, ferroelectric domain reversal from a +z spontaneous polarization to a −z spontaneous polarization in the surface of congruent LN (48.39mole% of Li2O). On the other hand, near-stoichiometric LN (49.9mole% of Li2O) did not develop repolarization during the identical thermal treatment. Furthermore, as determined in situ by spectroscopic ellipsometry, congruent LN (CLN) shows a bigger variation of the pseudorefractive index and pseudoextinction coefficient during annealing at various temperatures in the range of 100–800°C, indicating surface modification at those temperatures. On the other hand, near-stoichiometric LN (SLN) shows little change in these indexes implying that SLN provides better surface stability at elevated temperatures in the vacuum environment. This improved vacuum tolerance of SLN has allowed Al0.20Ga0.80N∕GaN heterostructures to be grown on CLN and SLN substrates, with two times higher channel mobility resulting on SLN substrates. Thus, SLN appears to be a viable substrate for molecular beam epitaxial growth of III-nitrides in various applications.

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Section: Vacuum Outgassing Effect On the Surface Of Lithium Niobatementioning

confidence: 96%

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

Lee¹,

Namkoong²,

Doolittle³

et al. 2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…Past studies have found that thin crystalline films of LiNbO 3 are partic-ularly sensitive to high annealing temperatures [50,51], suggesting that similar effects might be observed for powders. Furthermore, while bulk crystals generally require reducing atmospheres [52] or vacuum [53] for significant oxygen to diffuse out of the crystal matrix during annealing, we found that in small crystallites the out diffusion occurs even when annealed in an ambient atmosphere, resulting in black powders. To prevent the loss of oxygen from the material, we annealed the powders under a continuous flow of oxygen (ultra-high purity grade), a method that has been shown to inhibit the reduction process for bulk crystals [53], although for thin films there have been some indications that excess oxygen may potentially be absorbed and produce defects [54].…”

Section: Sample Preparationmentioning

confidence: 83%

Effects of mechanical processing and annealing on optical coherence properties ofEr3+:LiNbO3 powders

Lutz

Veissier

Thiel

et al. 2017

Journal of Luminescence

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Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er 3+ :LiNbO3) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are used to assess the coherence lifetimes for these highly scattering media. Direct intensity or heterodyne detection of two-pulse photon echo techniques was employed for samples with longer coherence lifetimes and larger signal strengths, while time-delayed optical free induction decays were found to work well for shorter coherence lifetimes and weaker signal strengths. Spectral hole burning techniques were also used to characterize samples with very rapid dephasing processes. The results on powders are compared to the properties of a bulk crystal, with observed differences explained by the random orientation of the particles in the powders combined with new decoherence mechanisms introduced by the powder fabrication. Modeling of the coherence decay shows that paramagnetic materials such as Er 3+ :LiNbO3 that have highly anisotropic interactions with an applied magnetic field can still exhibit long coherence lifetimes and relatively simple decay shapes even for a powder of randomly oriented particles. We find that coherence properties degrade rapidly from mechanical treatment when grinding powders from bulk samples, leading to the appearance of amorphous-like behavior and a broadening of up to three orders of magnitude for the homogeneous linewidth even when low-energy grinding methods are employed. Annealing at high temperatures can improve the properties in some samples, with homogeneous linewidths reduced to less than 10 kHz, approaching the bulk crystal linewidth of 3 kHz under the same experimental conditions.

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“…Beyond integrated lasers, the platform can also be used to realise other devices, such as photonic switching networks for photonic computing [55] or boson sampling [56], as well as integrated transceivers that combine hybrid integrated narrow linewidth lasers with lithium-niobate-based integrated IQ-modulators. The wide transparency window of both lithium niobate [15] and silicon nitride [57,58], moreover, allows such frequency agility to be extended to other wavelength ranges such as the mid-infrared or the visible, providing a platform for fast tunable lasers for applications ranging from optical coherence tomography [37] to trace gas sensing [59].…”

Section: Discussionmentioning

confidence: 99%

“…Lithium niobate is an attractive material for electrooptic devices, and has been widely used for many decades. It exhibits a transparency window from ultravi-olet to mid-infrared wavelengths and has a large Pockels coefficient [15,16], which is key for efficient, low-voltage, and high-speed modulation. Integrated photonics based on materials exhibiting the Pockels effect -such as AlN [17] and GaP [18] -have been demonstrated before, but only recently for lithium niobate [19,20].…”

mentioning

confidence: 99%

Ultrafast tunable lasers using lithium niobate integrated photonics

Snigirev¹,

Riedhauser²,

Lihachev³

et al. 2021

Preprint

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Optical properties of reduced LiNbO₃

Cited by 34 publications

References 45 publications

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

Effects of mechanical processing and annealing on optical coherence properties ofEr3+:LiNbO3 powders

Ultrafast tunable lasers using lithium niobate integrated photonics

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Optical properties of reduced LiNbO3

Cited by 34 publications

References 45 publications

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

Effects of mechanical processing and annealing on optical coherence properties ofEr3+:LiNbO3 powders

Ultrafast tunable lasers using lithium niobate integrated photonics

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Optical properties of reduced LiNbO₃