Single-lobed far-field pattern operation in a phased array with an integrated phase shifter

Abstract

A phased array with an integrated phase shifter which can convert a 180° phase mode into an in-phase mode was demonstrated. An Al2O3 facet coating with a different thickness on each array element was performed. It should act as the phase shifter. A stable single-lobed far-field pattern was obtained from the array with the phase shifter.

High-brightness diode laser arrays integrated with a phase shifter designed for single-lobe far-field pattern

“…3(a) and the output power up to 465 mW∕facet is achieved, which is one of the best reported results for high-brightness devices integrated with the phase shifter [14][15][16]. The threshold current is 390 mA and the external differential efficiency is 22%.…”

“…Superior to other phase shifters fabricated by facet coating and plate mounting [14,15], the integrated phase shifter in our device is easy to achieve technically, and it also reduces the bend loss in the curved waveguide arrays [16]. Although the carrier-induced variations of refractive index are avoided in the passive phase-shift region, the thermal effect generated by the absorption loss strongly affects the device performance.…”

“…Known approaches to solve this problem include the antiguided laser arrays [10], Y-junction laser arrays [11], and laser arrays with collimation microlens [12] or external Bragg gratings [13], but a huge optical system, complicated epitaxial growth process, or large radiation losses usually result, which affects device yield and robustness. Phase-shift structures have been applied to phase-locked laser arrays to convert the two-lobe pattern into single-lobe one, such as an external phase-shift plate [14] or an integrated phase-shift facet coating [15]. One report by Elarde et al…”

Semiconductor photonic crystal laser

“…Phase-shift structures, such as an external phase-shift plate [58] or an integrated phase-shift facet coating, [59] have been applied to phase-locked laser arrays to convert a twolobe pattern into a single-lobe one. Zheng et al [60] developed a laser that contained a coupling region and a mode conversion region.…”

Comprehensive design and analysis of diode laser arrays with an integrated phase shifter

“…Some of these attempts show prominent performance but require complicated fabrication process or rather large external optical system where high cost or punctilious alignment are inevitable, and the others demonstrate relatively poor characteristics such as low power, instability, or operation only under pulse mode which restricts the application area. Design of phase-locked diode laser arrays with integrated phase-shifters was firstly proposed by Ackley et al [10] and devices were experimentally achieved with an external phase-shift plate [11][12][13], or an integrated phaseshift facet coating [14]. A three-region design with curved waveguides as an integrated phase-shifter was reported to achieve the on-axis, diffraction-limited beam pattern, but only a low power in pulse mode was obtained [15].…”