Low phonon energy, Nd:LaF/sub 3/ channel waveguide lasers fabricated by molecular beam epitaxy

Abstract

Abstract-We report the first fabrication and laser operation of channel waveguides based on LaF 3 planar thin films grown by molecular beam epitaxy. To our knowledge, this is the lowest phonon energy dielectric material to have shown guided-wave laser operation to date. A full characterization, in terms of spectroscopy, laser results, and propagation losses, is given for the planar thin films upon which the channel waveguides are based. Two channel-fabrication methods are then described, the first involves ion milling and the second takes the novel approach of using a photo-definable polymer overlay. Laser operation in Nd-doped samples is demonstrated at 1.06, 1.05, and 1.3 m, and the potential for mid-infrared laser sources based on such guides is discussed.

Optically pumped planar waveguide lasers, Part I: Fundamentals and fabrication techniques

“…Although there are reports in the literature on MBE growth of waveguide films of complex ternary oxide materials such as LiNbO 3 [120] and BaTiO 3 [121], most of the work on dielectric waveguide layers to date has focused on hetero-epitaxial deposition of rare-earth doped fluoride waveguides, such as ZnF 2 , PbF 2 , [122] CaF 2 , [123] and LaF 3 [124][125][126][127]. They were grown on different dielectric and semiconductor substrates and their propagation loss was on the order of 1 dB·cm -1 [122,126,127].…”

“…They were grown on different dielectric and semiconductor substrates and their propagation loss was on the order of 1 dB·cm -1 [122,126,127]. Reports on waveguide lasers are limited to LaF 3 :Nd 3+ structures with slab and channel geometries [126,127].…”

“…They were grown on different dielectric and semiconductor substrates and their propagation loss was on the order of 1 dB·cm -1 [122,126,127]. Reports on waveguide lasers are limited to LaF 3 :Nd 3+ structures with slab and channel geometries [126,127]. The reasons behind this interest in implementing this method for growth of fluoride crystal layers rather than for their oxide counterparts are: (i) the fluoride molecules have a higher dissociation energy, and therefore can withstand the processes of evaporation and transport to the substrate without decomposing, and (ii) the combination of the low temperatures required for growth of fluoride layers and the inherently low growth rates of the MBE method ensures homogeneous distribution of the rare earth ions within the layers and thus minimization of clustering.…”

Tm 3 + -doped ion-exchanged aluminum germanate glass waveguide for S-band amplification

“…In glass substrate, ultralow transition temperature in tellurite glasses, large crystallization tendency in gallate glasses, and poor acid resistibility in nonoxide glasses block the attempts in low phonon energy glass waveguide seriously. [15][16][17][18] In RE activators, illustrated by the case of S-band amplification of Tm 3+ , 3 H 4 → 3 F 4 transition is medisensitive to phonon energy and lower phonon energy hosts have to be employed to achieve the efficient emission. Meanwhile, exorbitant concentration doping of Tm 3+ should be avoided to reduce ͓ 3 H 4 , 3 H 6 ͔-͓ 3 F 4 , 3 F 4 ͔ cross-relaxation rate between Tm 3+ ions, which is necessary for maintaining S-band emission efficiency.…”

Green, orange, and red Pr^3+∶YLiF_4 epitaxial waveguide lasers

“…Crystalline fluoride thin films were first fabricated by molecular beam epitaxy (MBE) and were used as crystalline insulators in semiconductor/insulator/semiconductor heterostructures for integrated circuits and optoelectronic devices [2,3]. More recently, waveguide laser oscillation has been reported in crystalline rare-earth-doped fluoride layers fabricated by MBE [4,5] and liquid phase epitaxy (LPE) [6][7][8].…”