^newsbreaks
Rotary-disk laser
betters its own record

After demonstrating early last year a record-high-

power Q-switched diode-pumped solid-state (DPSS)

laser— 72. 8 W at 50 kHz in 69 ns pulses for an ytter-

bium-yttrium aluminum garnet ( Yb-YAG) rotary-disk

laser at 1030 nm (see www.laserfocusworld.com/

articles/245257)—researchers at Sparkle Optics

(Rolling Hills Estates, CA) have achieved two more

milestones by demonstrating a 214 W Q-switched dif-

fraction-limited laser at 1030 nm at 43% optical effi-

ciency and an 87 W diffraction-limited laser at 515 nm

that operates from 40 to 100 kHz at 18% optical ef-

ficiency. The high-power pulsed rotary-disk laser at

the fundamental wavelength of 1 µm will enable high-

power laser sources from deep-ultraviolet to long-wave

infrared in the near future.

The introduction of motion in the design of solid-

state lasers overcomes the thermal limitation in power

scaling of bulk solid-state devices, and the use of a

free-space resonator overcomes the mode-area limita-

tion of fiber lasers for pulsed applications. A 1030 nm

laser operating at 85 W has been used to drill 60 µm

holes in 3-mm-thick type 304 stainless steel in 3. 4 sec-

onds, which is a much faster drilling rate than the tradi-

tional EDM (electrical-discharge-machining) processes.

Contact Santanu Basu at basu@sparkleoptics.com.

Study of nonlinear dynamics
may contribute to PIC design

Using an integrated colliding-pulse modelocked semi-

conductor-laser array, researchers at Technische Univer-

siteit Eindhoven (The Netherlands) have demonstrated a

period-doubling transition into chaos, indicating the ex-

istence of nonlinear dynamics in photonic integrated cir-

cuits (PICs). A lensed fiber was used to collect light from

the laser-output waveguides; the signal was amplified

using a semiconductor optical amplifier.

The researchers recorded the radio-frequency spectrum

of the laser and performed a so-called Fokker-Planck analy-

sis to reconstruct the deterministic content of the laser-out-

put dynamics. They observed intrinsic nonlinear dynamics in

the integrated active-photonic device under study. They also

noted no less of a tendency toward nonlinear dynamics than

in nonintegrated lasers consisting of individual optical com-

ponents. Nonlinear dynamics actually play a major role in the

function of photonic integrated laser circuits, according to

the researchers. Consequently, analysis and visualization of

nonlinear dynamics are expected to contribute to improved

design of photonic integrated circuits. In comparison to

stand-alone photonic devices, the dynamics of PICs appear

to be more stable over the lifetime of the system, reproduc-

ible from batch to batch, and on faster time scales because

of the small sizes of PICs, according to the researchers.

Contact Mirvais Yousefi at m.yousefi@tue.nl.

Capillary-condensation-based optical switch is bistable

Researchers at the European Laboratory for Nonlinear Spectroscopy and

2.0

INFM-BC (Florence, Italy) and the University of Trento (Trento, Italy) have de- _Experimental veloped a novel form of optical switch that relies on the interaction of light _{1. 5 Simulation} with capillary condensation of organic vapors in photonic structures. The ap-

proach leads to optical bistability (which makes for a switch that more reliably _1.0 remains in its on or off state).

An optical superlattice fabricated from porous silicon has pore sizes that _0.5 P_th2 fall in the tens-of-nanometers range, which is on the order of the diameter for vapor condensation at room temperature. The superlattice has a periodic mod- 0.0 P_th1 ulation in refractive index overlaid on a linear index gradient, creating a photonic 0 5 10 15 20

structure for which the photonic-band central frequency depends on position.

As the organic vapor condenses, it partially fills the pores, changing the refractive-index gradient. Evaporation induced

by a 973-nm-emitting laser restores resonance. The bistability resulted from different thresholds for evaporation (P_th1) and condensation (P_th2). The 10 ms switching time could be reduced to the microsecond range by reducing device volume, say the researchers. Contact Pierre Barthelemy at barthelemy@lens.unifi.it.