Low loss depressed cladding waveguide inscribed in YAG:Nd single crystal by femtosecond laser pulses

Abstract

Abstract:A depressed cladding waveguide with record low loss of 0.12 dB/cm is inscribed in YAG:Nd(0.3at.%) crystal by femtosecond laser pulses with an elliptical beam waist. The waveguide is formed by a set of parallel tracks which constitute the depressed cladding. It is a key element for compact and efficient CW waveguide laser operating at 1064 nm and pumped by a multimode laser diode. Special attention is paid to mechanical stress resulting from the inscription process. Numerical calculation of mode distribution and propagation loss with the elasto-optical effect taken into account leads to the conclusion that the depressed cladding is a dominating factor in waveguide mode formation, while the mechanical stress only slightly distorts waveguide modes. ©2012 Optical Society of America

Control of the properties of micro-structured waveguides in lithium niobate crystal

“…The positive RI contrasts between exposed and unexposed areas that are typically induced by direct fs writing in optical glasses [3] can be up to an order of magnitude higher than those of optical fibres [15]. Continuous, smooth tracks can also be inscribed in various crystal materials [3,5,6,11,16,17], featuring reduced RI in the central area of the track and slightly increased RI in the surrounding region [18]. Single tracks in crystals may exhibit waveguiding properties, but guidance occurs only in the surrounding areas of residual stress left within the material by the laser beam passage [3].…”

“…But such a WG structure does not allow for control over the waveguiding properties. On the other hand, due to geometric flexibility, the depressed cladding may consist of a fairly large number of arbitrarily arranged tracks confining the flexibly large and shaped core guiding area [17]. Depressed-cladding WGs have been demonstrated to achieve light propagation with good mode confinement at different wavelengths, and low propagation losses as compared with directly written, single-track WGs [5,6,10,17,19].…”

“…On the other hand, due to geometric flexibility, the depressed cladding may consist of a fairly large number of arbitrarily arranged tracks confining the flexibly large and shaped core guiding area [17]. Depressed-cladding WGs have been demonstrated to achieve light propagation with good mode confinement at different wavelengths, and low propagation losses as compared with directly written, single-track WGs [5,6,10,17,19]. It has also been proved that depressed-cladding WGs in nonlinear crystals can achieve enhanced-efficiency secondharmonic generation as compared with stress-induced WGs [20,21].…”

Compact Cr:ZnS Channel Waveguide Laser Operating at 2360 nm

“…The waveguide design was an annular cross-section depressed cladding structure fabricated from an arrangement of individual modification elements similar to the design previously demonstrated in Nd: YAG [23] and Cr:ZnSe [24]. A schematic diagram of the waveguide cross-section is displayed in Fig.…”

Fluorescence imaging of lattice re-distribution on step-index direct laser written Nd:YAG waveguide lasers

“…10 In other cases, waveguiding is produced by a low-index cladding. 13,14 Both types of structures are typically fabricated using low-repetition rate lasers (1 kHz) and have been successfully used for the demonstration of efficient Nd:YAG waveguides lasers operating at 1.06 lm ( 4 F 3/2 ! 4 I 11/2 transition of Neodymium ions).…”