P. K. Tien

MODES OF PROPAGATING LIGHT WAVES IN THIN DEPOSITED SEMICONDUCTOR FILMS

We report theory and experiment on modes of propagating light waves in deposited semiconductor films. The modes are excited by a novel prism‐film coupler which is also used for the measurement of their phase velocities. Up to 50% of the incident laser energy has been fed into a single mode of propagation. The positions and linewidths of the modes, the wave intensity inside the film, and a dramatic view of the mode spectrum displayed by the scattered light are discussed in detail.

OPTICAL SECOND HARMONIC GENERATION IN FORM OF COHERENT CERENKOV RADIATION FROM A THIN‐FILM WAVEGUIDE

We report optical second harmonic generation in form of coherent Cerenkov radiation. The fundamental wave at 1.06 μm propagates in a thin‐film optical waveguide which is simply a ZnS film vacuum‐deposited on a single‐crystal ZnO substrate. The nonlinear polarization excited in the substrate has a phase velocity exceeding that of radiation propagating freely in the substrate material. It thus acts as the source of the observed Cerenkov radiation.

Switching and modulation of light in magneto‐optic waveguides of garnet films

We report for the first time switching and modulation of light in a magneto‐optic waveguide that is a single‐crystal epitaxially grown iron‐garnet film. These experiments involve the Faraday rotation of the magnetic film and the motion of magnetization in the plane of the film. We have modulated light from a 1.152‐μm laser up to 80 MHz. We were also able to switch light between two waveguide modes by applying a magnetic field as small as 0.2 Oe.

Optical waveguides of single‐crystal garnet films

We report light‐wave propagation experiments in single‐crystal epitaxially grown garnet films. The discussion includes refractive index and lattice constant considerations for various garnets, and also the use of iron garnet films on gallium garnet substrates as magneto‐optical waveguides useful in integrated optics.

Optical waveguide modes in single‐crystalline LiNbO3–LiTaO3 solid‐solution films

We report new LiNbO3–LiTaO3 solid‐solution films which form excellent active optical waveguides. Measurement of the waveguide modes indicates that these films have a graded composition. To analyze these waveguides, we present a theory for the calculation of the mode indices and find that the refractive index varies with the depth in the film, according to a Fermi function.

EXPERIMENTS ON LIGHT WAVES IN A THIN TAPERED FILM AND A NEW LIGHT‐WAVE COUPLER

We discuss experiments in an asymmetric optical waveguide which is simply a dielectric film deposited on a substrate. The film has a tapered edge. Near this edge and depending on the angle of incidence, a guided light wave in the film may be totally reflected or it can enter into the substrate as radiation modes. In the latter case, the tapered film edge is used here to couple light energy into or out of the film.

The growth of LiNbO3 thin films by liquid phase epitaxial techniques

Abstract We report a liquid phase epitaxial dipping process for the growth of thin films of ferroelectric LiNbO 3 on isostructural LiTaO 3 substrates. These single crystalline films ranging from 1 to 10 μm in thickness form excellent low loss optical waveguides and have a desired sharp step change of index of refraction with the LiTaO 3 substrate. We discuss the phase stability diagrams for the flux systems used in the dipping process along with the growth parameters which affect the film quality.

Light beam scanning and deflection in epitaxial LiNbO3 electro‐optic waveguides

We report a method of scanning and deflecting a light beam in an electro‐optic waveguide of epitaxial LiNbO3 film. The method involves the use of the electro‐optic effect for excitation of a proper distribution of the refractive index which causes the light beam to deflect. The angle of deflection is found to vary continuously with the intensity of the applied field. We are able to scan a light beam in the plane of the film up to 4°. We also present a theory for the light beam deflection and show that our method does optimize the deflection efficiency.