High-gain Al2O3:Nd3+ channel waveguide amplifiers at 880 nm, 1060 nm, and 1330 nm

Abstract

Neodymium-doped aluminum oxide films with a range of Nd 3+ concentrations are deposited on silicon wafers by reactive co-sputtering, and single-mode channel waveguides with various lengths are fabricated by reactive ion etching. Photoluminescence at 880, 1060, and 1330 nm from the Nd 3+ ions with a lifetime of 325 µs is observed. Internal net gain at 845-945 nm, 1064, and 1330 nm is experimentally and theoretically investigated under continuous-wave excitation at 802 nm. Net optical gain of 6.3 dB/cm at 1064 nm and 1.93 dB/cm at 1330 nm is obtained in a 1.4-cm-long waveguide with a Nd 3+ concentration of 1.68 × 10 20 cm −3 when launching 45 mW of pump power. In longer waveguides a maximum gain of 14.4 dB and 5.1 dB is obtained at these wavelengths, respectively. Net optical gain is also observed in the range 865-930 nm and a peak gain of 1.57 dB/cm in a short and 3.0 dB in a 4.1-cm-long waveguide is obtained at 880 nm with a Nd 3+ concentration of 0.65 × 10 20 cm −3 . By use of a rate-equation model, the gain on these three transitions is calculated, and the macroscopic parameter of energy-transfer upconversion as a function of Nd 3+ concentration is derived. The high internal net gain indicates that Al 2 O 3 :Nd 3+ channel waveguide amplifiers are suitable for providing gain in many integrated optical devices.

Carrier generation using a dual-frequency distributed feedback waveguide laser for phased array antenna (PAA)

“…5a shows the measured laser power as a function of the diode pump current. Due to the misalignment of WDM fiber with respect to the waveguide the measured laser power is much lower than what is actually emitted out of the waveguide [22]. The beat frequency as a function of diode pump current is shown in Fig.…”

Nanowatt threshold, alumina sensitized neodymium laser integrated on silicon

“…3(a)). These emitted wavelengths correspond to stimulated emission from the 4 F 5/2 energy level to the 4 I 9/2 and 4 I 11/2 levels, respectively [4,5]. It is important to note that the number of observed lasing peaks (hence, the number of lasing modes) depends on many factors, including the coupling, input power, dopant concentration, device materials, and geometry.…”

“…First, using a single pump source, it is possible to generate a wide range of emission wavelengths due to the multiple excitation and decay pathways of rare earth ions. For example, when neodymium is pumped near 800nm, lasing near 900-940nm, 1050-1150nm, and ~1330nm can be observed [4][5][6]. Second, rare earth ions have very large absorption cross sections for excitation.…”

“…This approach requires the transformation of fiber laser systems into integrated microscale devices. One straightforward approach is to use integrated waveguides in lieu of optical fiber [5,7,8]. However, the optical loss of integrated waveguides, which affects the laser threshold, is significantly higher than optical fiber.…”

Spectroscopic excitation and quenching processes in rare-earth-ion-doped AI203 and their impact on amplifier and laser performance

“…Energy-transfer upconversion (ETU), often assisted by energy migration (both described in Chapter 2), has a significant impact on the amplifier or laser performance of a number of rare-earth-ion-doped compounds by depleting the population of the longlived upper state of the corresponding luminescence transition, thereby diminishing the available optical gain [69][70][71][72][73][74][75][76][77][78]. ETU can also be exploited to deplete the lower laser level [79][80][81][82] or generate upconversion luminescence and lasing [83][84][85][86][87].…”