Efficient photorefractive effect triggered by pyroelectricity in magnesium doped LiNbO3 films.

An efficient photorefractive effect triggered by pyroelectricity is demonstrated in slab waveguides constituted of magnesium oxide (MgO)-doped LiNbO3 film on insulator. A microwatt-level continuous wave guided at 532 nm is self-trapped to form a 10 µm FWHM beam triggered by only a few degrees of temperature increase of the sample. A fast self-focusing response time on the order of milliseconds is measured for milliwatts of injected beam, more than two orders of magnitude faster than in the undoped LiNbO3 film. Long lived 2-D induced waveguides are found to be written in the films.

Birefringence phase-matched direct third-harmonic generation in a ridge optical waveguide based on a KTiOPO4 single crystal.

Birefringence phase-matched third-harmonic generation at 1594 nm is performed for the first time in a KTiOPO4 single crystal micrometric ridge waveguide. The energy conversion efficiency reaches 3.4% for a pump energy as low as 2 µJ over a pulse duration of 15 ps at a repetition rate of 10 Hz. Strong agreements between theory and experiments for both phase-matching and conversion efficiency is obtained, which let us envision future triple photon generation quantum experiments.

Single photon MIR upconversion detector at room temperature with a PPLN ridge waveguide.

In this paper we describe an upconversion detector in the mid infrared (around 3.5 µm). We take advantage of the PPLN ridge waveguide technology to achieve single photon detection at room temperature on a single spatial mode. With a pump power of 192 mW we obtain a detection efficiency of 0.4% for 22k dark count per second, which corresponds to a noise equivalent power of 3.0 fW · Hz-1/2 and an internal conversion efficiency of 85 %/W of pump.

Phase-matched second-harmonic generation in a flux grown KTP crystal ridge optical waveguide.

Type II second-harmonic generation was performed in a 15.8-mm-long KTiOPO4 (KTP) micrometric ridge waveguide with an average transversal section of 38 µm2. Theoretical predictions are compared with experiments. Strong agreements are obtained for both phase-matching wavelengths and second-harmonic intensity. This work opens wide perspectives for integrated parametric optics.

Fast-beam self-trapping in LiNbO(3) films by pyroelectric effect.

We report light-beam self-trapping triggered by the pyroelectric effect in an isolated ferroelectric thin film. Experiments are performed in an 8-µm-thick congruent undoped LiNbO(3) film bonded onto a silicon wafer. Response time two orders of magnitude faster than in bulk LiNbO(3) is reported. The original underlying physics specific of this arrangement is discussed.

Acoustic resonator based on periodically poled lithium niobate ridge.

The constant improvement of industrial needs to face modern telecommunication challenges leads to the development of novel transducer principles as alternatives to SAW and BAW solutions. The main technological limits of SAW (short-circuit between electrodes) and BAW (precise thickness control) solutions can be overcome by a new kind of transducer based on periodically poled ferroelectric substrate. The approach proposed in this paper exploits a ridge structure combined with a periodically poled transducer (PPT), allowing for the excitation of highly coupled modes unlike previously published results on planar PPTs. High-aspect-ratio ridges showing micrometer dimensions are achieved by dicing PPT plates with a diamond-tipped saw. An adapted metallization is achieved to excite acoustic modes exhibiting electromechanical coupling in excess of 15% with phase velocities up to 10 000 m·s(-1). Theoretical predictions show that these figures may reach values up to 20% and 18 000 m·s(-1), respectively, using an appropriate design.

Acoustic wave filter based on periodically poled lithium niobate.

Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-µm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms(-1), respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.