Diffraction characteristics of general dielectric planar (slab) gratings and surface-relief (corrugated) gratings are reviewed. Applications to laser-beam deflection, guidance, modulation, coupling, filtering, wavefront reconstruction, and distributed feedback in the fields of acoustooptics, integrated optics, holography, and spectral analysis are discussed. An exact formulation of the grating diffraction problem without approximations (rigorous coupled-wave theory developed by the authors) is presented. The method of solution is in terms of state variables and this is presented in detail. Then, using a series of fundamental assumptions, this rigorous theory is shown to reduce to the various existing approximate theories in the appropriate limits. The effects of these fundamental assumptions in the approximate theories are quantified and discussed.

Analysis and applications of optical diffraction by gratings

Integrated optics and new wave phenomena in optical waveguides

The fraction of spontaneous emission going into an oscillating laser mode has been calculated. It is shown that this fraction strongly depends on the strength of astigmatism in the laser output beam. Therefore the spontaneous emission factor in planar stripe lasers with narrow stripe is in the order of 10-4and by one order of magnitude larger than in injection lasers with a comparable active layer volume and with a built-in index waveguide. It is shown that the spontaneous emission factor is approximately proportional to the solid angle of laser radiation and nearly independent of the transverse active layer dimensions. Owing to the large spontaneous emission factor, the spectral width of narrow planar stripe lasers is significantly broader compared to narrow stripe lasers with a built-in index waveguide. In addition the large spontaneous emission coefficient also yields a much stronger damping of relaxation oscillations.

Calculated spontaneous emission factor for double-heterostructure injection lasers with gain-induced waveguiding

The theory and recent applications of waves in periodic structures are reviewed. Both the Floquet and coupled waves approach are analyzed in some detail. The theoretical part of the paper includes wave propagation in unbounded and bounded active or passive periodic media, wave scatterring from periodic boundaries, source radiation (dipole, Cerenkov, transition, and Smith-Purcell) in-periodic media, and pulse transmission through a periodic slab. The applications part covers the recent development in a variety of fields: distributed feedback oscillators, filters, mode convertors, couplers, second-harmonic generators, deflectors, modulators and transducers in the fields of integrated optics and integrated surface acoustics. We also review the work on insect compound eyes, mehanical structures ocean waves, pulse compressions, temperature waves, and cholestric liquid crystals. Particles interaction with crystals is briefly reviewed, especially in the case of zeolite crystals and supelattices. Recent advances in fabrication techniques for very fine gratings me also covered. Finally, speculations about future problems and development in the field of waves in periodic structures are given.

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Waves in active and passive periodic structures: A review

This paper deals with the theory and device applications of periodic thin-film waveguides. Topics treated include mode solutions, optical filters, distributed feedback lasers (DFB), distributed Bragg reflector (DBR) lasers, grating couplers, and phase matching in nonlinear interactions.

/pdf/periodic-structures-for-integrated-optics-inegvy8lro.pdf

Periodic structures for integrated optics

A frequency multiplexing light source is realized by monolithically integrating GaAs‐GaAlAs distributed‐feedback diode lasers with different grating periods and passive waveguides on a GaAs substrate. The lasers with wavelength separation of ∼20 A are modulated independently, and the output beams are obtained from a common launching waveguide.

Frequency multiplexing light source with monolithically integrated distributed‐feedback diode lasers

We report laser oscillation at 80–100°K in electrically pumped GaAs–Ga1−xAlxAs double‐heterostructure distributed‐feedback diode lasers. The feedback for laser oscillation was provided by a corrugated interface between the active GaAs layer and the p‐Ga1−xAlxAs layer. The lowest threshold current density was 2.5 kA/cm2 in pulsed operation. The wavelength of laser emission was 8112 A at 82°K with a half‐width of less than 0.3 A. The temperature dependence of the laser wavelength was found to be smaller than that of the conventional Fabry‐Perot laser.

GaAs–Ga1−xAlxAs double‐heterostructure distributed‐feedback diode lasers

Monolithic integration of a GaAlAs laser with a GaAs Schottky‐gate field effect transistor is demonstrated. A GaAs field effect transistor with a 3‐μm gate length is formed on a double‐heterostructure laser crystal which is protected by a high‐resistivity isolation layer. Laser light intensity is modulated to realize rise and fall times of less than 0.4 ns by modulating the field effect transistor gate voltage.

Monolithic integration of a GaAlAs injection laser with a Schottky-gate field effect transistor

Transverse-mode stabilized visible diode lasers in the 0.7-μm wavelength region are fabricated by growing a Ga1−xAlxAs double heterostructure on a grooved GaAs substrate (channeled-substrate-planar structure). The diodes operate stably in the fundamental transverse mode and provide nonstigmatic laser beams. They can be collimated with a 0.5–1-mrad beam divergence using a simple graded-index fiber lens. Corresponding to single-longitudinal-mode operation at current levels above 1.1 times the threshold, a coherence length as long as 14 m is obtained in Michelson interference experiments.

Transverse-mode stabilized Ga(1-x)Al(x)As visible diode lasers.

The waveguide mechanism in channeled-substrate-planar (CSP) structure (AlGa)As lasers is analyzed. The light leakage into the GaAs substrate outside the channel is shown to provide effective refractive index and loss differences, which function to stabilize the transverse mode in the junction plane. Observed light output vs current characteristics and mode patterns in the lasers justify the theoretical model.

M. Nakamura

Papers

Frequency multiplexing light source with monolithically integrated distributed‐feedback diode lasers

GaAs–Ga1−xAlxAs double‐heterostructure distributed‐feedback diode lasers

Monolithic integration of a GaAlAs injection laser with a Schottky-gate field effect transistor

Transverse-mode stabilized Ga(1-x)Al(x)As visible diode lasers.

Channeled-substrate-planar structure AlxGa 1− x As lasers: an analytical waveguide study