Periodically poled stoichiometric lithium tantalate was used for an efficient green light generation based on frequency doubling of a pulsed Nd:YVO 4 laser. The achieved average peak power density of 9.2 MW/cm 2 was sufficiently stable without spatial distortion of green light at 532 nm at room temperature (33 C). A small phase matching temperature adjustment (0.5 C) was required at the maximum average output power of 4.4 W owing to its high thermal conductivity.
Effective optical parametric oscillation (OPO) at room temperature was demonstrated by a periodically poled 1.0 mol% MgO-doped stoichiometric lithium tantalate (Mg:SLT) crystal. The slope conversion efficiency of total output power was ∼65% and the maximum output power was 655 mW at 1.3 W pumping without photorefraction. The difference of the OPO performance was investigated between 0.5 and 1.0 mol % Mg:SLT crystals, and a 1.0 mol % MgO-doped device exhibited better OPO performance and high resistance of photorefraction. The effective nonlinear coefficient of deff was found to be 10pm∕V by single-pass first-order quasiphase matched second-harmonic generation at 1064 nm.
A 35-mm-long periodically poled device was fabricated from a near-stoichiometric lithium tantalate, and optical parametric oscillation was demonstrated with a low oscillation threshold (106 mW). The emitted signal and idler wavelengths were 1.53–1.63 and 3.06–3.49 μm, respectively, and the highest slope conversion efficiency was 65% with a maximum output power of 628 mW at 1.1 W pumping. The influence of Curie temperature inhomogeneity on fabrication of the device was investigated to improve poling quality in long devices.
The rearrangement of the domain structure induced by chemical etching has been observed in periodically poled MgO-doped stoichiometric lithium tantalate single crystals. Topographic and piezoresponse scanning probe microscopy have been used for measuring the etching relief height and domain wall position after etching. The considerable shift of the domain wall during etching by pure hydrofluoric acid has been revealed by analysis of the experimental data. We have found that the wall motion proceeded after the termination of the etching procedure. We have shown that the whole consequence of the domain wall positions during etching is recorded in the etching relief height and can be extracted with high spatial and temporal resolution.
We developed the world smallest OLED microdisplay projection device. This device consists of just 2 parts which a high‐brightness Microdisplay based Organic Light Emitting diodes on a silicon backplane panel (M‐OLED) ( 1,000,000 [cd/m2] ) and an optimal lens (F/1.1) for the self‐emitting projection device.
This high‐ brightness M‐OLED is used 2 key technologies.
The first is a supplying the photoexitation potential to multiple emitting layers in OLED using by the new pixel transistor (Tr.) that can withstand very high voltage in 7.8 pm pixel. The second is the controlling light divergence angle from each self‐emitting pixel that made using micro optical resonance effect from cathode until anode electrode in OLED and the optimized micro lens (ML) for each pixel.
Next, we evaluated the relationship between the light divergence angle from M‐OLED and F number (Fno.) of the projection lens and we found parameters and a specific method for controlling the light efficiency of the self‐emitting projection device.
Based on the results of these fundamental studies, we established a design methodology for the self‐emitting projection device with high efficiency, and we realized the world smallest self‐emitting projection device (W 10 /D 11 /H 6 (mm)).
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