Thomas J. Roth

Phase-locked arrays of antiguides: model content and discrimination

Three classes of array modes of closely spaced antiguides are analyzed: coupled fundamental (element) modes, coupled first-order (element) modes, and modes adjacent to coupled fundamental modes. The behavior of coupled fundamental modes as a function of lateral index step is analyzed and explained from a ray-optics point of view. It is found that at resonance, for both coupled fundamental and first-order modes, the array-mode propagation constant is virtually identical to the propagation constant of the mode of a single, unperturbed antiguide. Several types of mode discrimination mechanisms are discussed. For devices with 3- mu m-wide antiguide cores and 1- mu m interelement spacing, intermodal discrimination values of 15-20 cm/sup -1/ can be achieved. Excellent agreement is found between experimental data and theoretical predictions based on the effective-index method. >

Two-dimensional surface-emitting leaky-wave coupled laser arrays

Leaky-wave coupling has been used for the first time to phase-lock surface-emitting antiguided arrays in a two-dimensional (2-D) configuration. Small differences between the length of separate array sections can be compensated for by phase shifts induced by carrier injection between the sections. Both four- and nine-array-section devices, arranged in diamond-shaped patterns, were phase-locked. Four-array-section devices provide far-field patterns with 35% fringe visibility to 0.2-W pulsed output power. Higher spatial coherence (45% fringe visibility) to 3.9-W pulsed output power is obtained from nine-array-section devices. The large improvement in coherent power of the nine-array-section devices appears to be because they are parallel coupled. The inherent single-spatial-mode stability of resonant optical waveguide (ROW) arrays to high drive levels above threshold allows the application of a coupled-mode formalism to 2-D arrays of ROW devices. The modeling indicates that resonant 16-array-section devices produce 10 W of spatially coherent power. >

Modulation characteristics of high-power phase-locked arrays of antiguides

The small signal modulation characteristics, large signal modulation characteristics and dc noise spectra on 70 micron-wide 20-element high-power phase-locked arrays of antiguides are reported. The relaxation resonance frequency at 1.5 times threshold is found to be 1.65 GHz. Large-signal pulse modulation produced no distortion to the far-field characteristics. The dc noise spectra showed a damped shot noise resonance at 1.32 GHz for a dc bias level of 1.18 times threshold.

High-power coherent diode lasers

Diffraction-limited beam operation at high output power levels (0.5 W cw and 1.5 W pulsed) has been demonstrated from resonant-optical-waveguide (ROW) array structures. Uniphase mode operation is achieved without the need for active phase control. As a result, a reliable monolithic device capable of watt-range coherent output power is obtained.

0.36-W cw diffraction-limited-beam operation from phase-locked arrays of antiguides

Diffraction-limited beam operation at high output power levels (0.36 W cw and 1.5 W pulsed) have been demonstrated from resonant-optical-waveguide array structures. Uniphase mode operation is achieved without the need for active phase control. As a result, a reliable monolithic device capable of watt-range coherent output power is obtained.

Stabilized in-phase-mode operation from monolithic antiguided diode laser arrays

Stabilized in-phase mode oscillation is demonstrated from large-aperture 20-element antiguided diode laser arrays. 20-element resonant optical waveguide arrays emit 160 mW total power at 2.8 x I(th) in a diffraction-limited beam and have high spatial coherence across the entire array. CW operation of nonresonant 20-element array structures is demonstrated to high output power levels.