Diffraction Limited Far-field Pattern Research Articles

5-W CW diffraction-limited InGaAs broad-area flared amplifier at 970 nm

A broad-area flared amplifier is fabricated that produces 5-W continuous-wave (CW) at 972 nm in a single-lobed, diffraction-limited far-field pattern. A high-power, tunable diode laser is used as the injection source. An incident power of only 90-120 mW is required to saturate the gain of the amplifier.

Modal discrimination in leaky-mode (antiguided) arrays (diode lasers)

Presents on the fabrication of a ten-element antiguided (leaky-mode) diode laser array that operates in an in-phase mode with a diffraction-limited far-field pattern at drive currents up to 8.7 times the threshold current (pulsed) and an output power of 400 mW (both facets). This device evidences good discrimination against the out-of-phase leaky mode without the benefit of a 'Talbot' spatial filter, relying instead on mode-sensitive interelement losses in an overlying GaAs layer. This device has been studied using two numerical models. Results from the more realistic of the two models predict in-phase-mode operation for certain restricted ranges of waveguide dielectric constant, in agreement with experiment. This behavior is shown to result from resonances between the waveguide modes and the modes of the active region. These results suggest that improved yields would result from a different type of leaky-mode array employing smaller, rectangularly shaped waveguides. >

Coherent addition of AlGaAs lasers using microlenses and diffractive coupling

A near single-lobed far-field pattern was obtained from coherent operation of a nonevanescently coupled AlGaAs laser diode array. A diffractive microlens array collimated the individual beams to approximate a plane wave, and diffractive coupling from an external cavity mirror provided mutual coherence. A diffraction-limited far-field pattern was observed with 82% of the power contained in the central lobe. The method is directly applicable to two-dimensional laser arrays and can be implemented as a single thin optical element.

Phase-locked controlled filament laser

A broad area semiconductor laser with induced self-focusing in the form of a phase-locked array of filaments is demonstrated. The multifilamentary laser has a single lobed and nearly diffraction limited far-field pattern, for injection currents up to I≂1.85Ith.

Tailored-gain broad-area semiconductor laser with single-lobed diffraction-limited far-field pattern

We demonstrate a 60 μm-wide asymmetric tailored-gain broad-area semiconductor laser with a single-lobed diffraction-limited far-field pattern 2.5° wide. The method used to achieve gain tailoring may be used to create nearly arbitrary two-dimensional spatial gain distributions within a broad-area laser.