H. Reshef

Phase-locking phenomena in a radial multislot CO 2 laser array

An investigation of phase-locking phenomena in a multichannel, slab-type electrode, CO2 laser array is presented. External and self-phase-locking percentages of 90% and 60%, respectively, have been demonstrated. Azimuthally distributed radial injection within the central region of this gain geometry has been identified as the principal phase-locking mechanism. Fundamental optical modes are initiated simultaneously within each individual discharge slot via injection from this central core-oscillator region.

Phase locking in a multichannel radial array CO2 laser

Phase locking in an extended‐area, multichannel, radial array, carbon dioxide laser has been investigated. Preliminary self‐phase‐locking percentages as high as 62% were achieved with the device. The phase‐locking mechanism was determined to be the mutual optical coupling present within the central region of this geometry. As such, this region acted as a core oscillator to initiate a fundamental optical mode within each individual discharge slot.

Toric unstable CO 2 laser resonator: an experimental study

The output characteristics of a toric unstable resonator fitted to a multichannel stripline excitation system are presented. The resonator is shown to possess the usual advantages of a conventional unstable resonator plus the ability to modify the profile of the output beam by a simple change in the coupling aperture. Laser output parameters have been studied as a function of coupling fraction, magnification, and internal loss factors. Variations in the focal spot size as a function of the coupling aperture as well as resonator alignment sensitivity and polarization properties have been investigated.

Symmetry enhancement and spot-size reduction through radial beam stacking in a multichannel CO/sub 2/ laser array

The beam quality of a diffusion-cooled RF-excited radial-geometry CO/sub 2/-slab-laser array is investigated. The system is shown to negate many of the disadvantages inherent with slab lasers, namely, asymmetric beams, multiple focal spots, and linear polarization. In addition, the effective spot size is reduced as a result of radial stacking of the individual asymmetric but azimuthally distributed, incoherent, output beamlets. A performance demonstration with sheet-metal cutting has produced excellent results in terms of kerf width, depth of penetration, and cut directionality. >

Annular-coupled concave–convex stable resonator for large-volume high-quality energy extraction

A theoretical investigation of a stable concave-convex resonator configuration, which appears suitable for single-mode high-power energy extraction from large volume gain media, is presented. The design features annular output coupling with a surprisingly uniform near-field intensity distribution. The computer-based analysis, supported by preliminary experimental results, suggests that acceptable alignment tolerances are provided along with an unusually small beam divergence. With proper design, a far-field divergence of 0.5 mrad, encompassing near 80% of the total laser energy, appears feasible. Operational data, recently obtained with this optical extraction approach, have revealed a further important practical advantage over an unstable resonator, being far less prone to mode degradation and hot spot formation on optical component misalignment.

Multiple pass unstable resonator for an annular gain CO2 laser.

The design, construction, and operational characteristics of an optical resonator for an annular gain media are described. The system, developed for laser power extraction investigations in a new type of coaxial discharge geometry, features a folded multipass unstable resonator concept, fabricated from lightweight uncoated diamond-turned aluminum substrates. The resulting cw CO2 device incorporates excitation aspects of the nonself-sustained PIE excitation process in addition to a new magnetic discharge stabilization technique. Laser performance and output beam characteristics are presented.

Multichannel laser resonators - an experimental study

The output characteristics of several large-area multichannel unstable resonators are presented. The conventional unstable resonator and a novel toric unstable resonator, in both confocal and nonconfocal configurations, have been studied. Output beam profiles, optical energy extraction, beam focusability, resonator alignment properties and polarization states of the various resonators have been analysed in depth.

High-average power-pulsed performance of a multikilowatt PIE laser

The application of a burst-mode pulsed discharge technique to a large-volume, multikilowatt, PIE (photo-initiated, impulse-enhanced, electrically excited) carbon dioxide laser is described. A factor of two enhancement in average output power, up to the 10 kW level, was obtained using a burst duration of 1.2 ms and a repetition rate of 500 burst/s. The small signal-gain increased to essentially double that of the normal continuous-wave value. Gain profile information, together with details of the lasers power performance, as a function of various discharge parameters, is illustrated. These data clearly document the versatility of this unique and cost-effective burst-mode laser excitation process. >

A cost-effective solution for packaging the arrayed waveguide grating (AWG) photonic components

Precision laser machining technology was used to cut arrayed waveguide grating (AWG) devices from 6-in wafers by following their complex profiles in a fully automatic way. A substantial cost saving in components manufacturing was achieved by an obtained device-cutting yield of 100%. The profile-cut AWG devices have smooth cutting edges and their optical performances were found unaffected by the cutting. These devices were processed in the subsequent packaging process easily without adding cost. They were proven mechanically stable in their packaging in meeting the telecommunication standards even though they have irregular geometry.

Burst-mode gain switched technique for high peak and average optical energy extraction

The optical performance of a cw PIE CO(2) laser has been substantially improved through the adoption of a burst-mode gain switching technique. The approach has provided a doubling of the average beam power extractable from the device. With appropriate optimization, the process could possibly permit the attainment of pulsed energy extraction in the kilohertz range, and with average optical powers within the several tens of kilowatt category.