Characterisation and comparison between different S-bend shaped GaAs Y-branch distributed Bragg reflector lasers emitting at 976 nm

Abstract

Passive S-bend waveguides have been thoroughly studied in the past, however active S-bend structures such as those in Y-branch distributed Bragg reflector (DBR) ridge waveguide (RW) lasers have been paid little attention. In this work, different S-bend based Y-branch DBR lasers emitting at 976 nm are developed, and their electro-optical, spectral and spatial characteristics are characterised. In total, two types of active S-bend (sinusoidal, cosinusoidal) as well as singlebend cosinusoidal Y-branch DBR-RW laser structures are investigated and their performances are compared to a reference straight DBR-RW laser. It is shown that among the investigated devices, the Cos S-bend based Y-branch laser provides the highest single-mode output power. However, when considering the spatial characteristics, the experimental results suggest that the Sin S-bend based Y-branch laser offers the best beam quality, and should be used in applications where good spatial characteristics are important. Finally, the experimental beam parameters are compared to passive waveguide simulations.

Spatial filtering of a six-wavelength DBR-RW laser in a MOPA system

“…The MO has a super-large optical-cavity (SLOC) structure with an InGaAs single quantum well (SQW), sandwiched between AlGaAs waveguide and cladding layers. The exact dimensions as well as the material parameters are described elsewhere [12]. The MO is 4 mm long, has a RW width of 2.5 µm, etched down to ∼ 1370 nm for transverse mode filtering, and has a measured effective index of neff = 3.66.…”

“…This is e.g. realized in the so-called Y-branch DBR-RW lasers which provide dualwavelength emission [12]. These light sources are suitable for beat signal generation, shifted excitation Raman spectroscopy, and in terahertz frequency generation [13][14][15].…”

“…These light sources are suitable for beat signal generation, shifted excitation Raman spectroscopy, and in terahertz frequency generation [13][14][15]. The Y-branch lasers provide output powers of between 100 and 250 mW, depending on the emission wavelength and vertical structure [12,15]. In order to boost the output power, a master oscillator power amplifier (MOPA) system was previously reported [16].…”

Compact diode laser based light source with alternating dual-wavelength emission at 532 nm

“…Both near field profiles show a defined 4.8 µm wide central lobe (1/e 2 ) and distinct side lobes at opposite sides. The side lobe positions can be explained by the waveguide design of the Y-branch laser and are discussed in detail in [16]. Due to the intensity carried by the side lobes, the resulting central lobe power content is reduced to 52%, available for coupling into the nonlinear waveguide crystal.…”

Offset effect on the S-Bend structure losses and optimization of its size for integrated optics

“…Waveguides represent the base of most of the integrated circuits to improve their performance while reducing the components dimensions, but the curvature of the waveguides leads to a power loss and a constraint on a transmission ability. The S-Bend structures are widely used to combine different elements of a circuit in order to build a variety of optical component like splitter [1], lasers [2,3], couplers [4,5], switches [6,7] and modulators [8][9][10]. Many solutions have been suggested to decrease the losses, but to lessen bending loss, the bending radius has to be increased.…”