Chapter 6
Direct Femtosecond Laser Writing
of Optical Waveguides in Dielectrics
Feng Chen and Javier R. Vázquez de Aldana
Abstract By applying direct femtosecond laser writing, optical waveguides with
diverse configurations can be produced in various transparent dielectrics, including
glasses, single crystals, and ceramics. The focused ultrashort pulses interact with the
bulk matrix, resulting in modification of refractive index of the localized regions.
Both positive and negative index changes have been successfully utilized to generate
waveguiding effects. Owing to the capability and feasibility of direct femtosecond
laser writing, a number of waveguide devices have been fabricated in versatile optical
materials, which brings out intriguing applications in many areas. In this chapter, we
overview the fundamentals of the femtosecond laser writing of optical waveguides
in optical dielectrics and introduce the recent applications in selected topics.
6.1 Introduction
Optical waveguides with compact geometries are basic components in integrated
optics [1]. They are defined as regions or layers with high refractive index in comparison with their surroundings. In waveguides, the light fields can be confined in very
small volumes, reaching relatively high intensities. The advantages of waveguidebased devices are twofolds: First, the diffraction-free light propagation enables beam
guidance and tailoring in chip-scale devices, which leads to a number of applications
in many areas; and second, the tight confinement of light fields brings out enhanced
features of bulk features in waveguides [2]. In 1996, Davis et al. reported on the first
femtosecond laser-written waveguides in a few family glasses [3], and numerous
subsequent works have been performed towards waveguide fabrication in various
transparent materials [4]. As of yet, direct femtosecond laser writing/inscription has
F. Chen (B)
School of Physics, State Key Laboratory of Crystal Materials, Shangdong University, Jinan
250100, China
e-mail: drfchen@sdu.edu.cn
J. R. V. de Aldana
Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada,
University of Salamanca, Salamanca 37008, Spain
© Springer Nature Switzerland AG 2020
A. Hu (ed.), Laser Micro-Nano-Manufacturing and 3D Microprinting, Springer Series
in Materials Science 309, https://doi.org/10.1007/978-3-030-59313-1_6
185
Direct Femtosecond Laser Writing
of Optical Waveguides in Dielectrics
Feng Chen and Javier R. Vázquez de Aldana
Abstract By applying direct femtosecond laser writing, optical waveguides with
diverse configurations can be produced in various transparent dielectrics, including
glasses, single crystals, and ceramics. The focused ultrashort pulses interact with the
bulk matrix, resulting in modification of refractive index of the localized regions.
Both positive and negative index changes have been successfully utilized to generate
waveguiding effects. Owing to the capability and feasibility of direct femtosecond
laser writing, a number of waveguide devices have been fabricated in versatile optical
materials, which brings out intriguing applications in many areas. In this chapter, we
overview the fundamentals of the femtosecond laser writing of optical waveguides
in optical dielectrics and introduce the recent applications in selected topics.
6.1 Introduction
Optical waveguides with compact geometries are basic components in integrated
optics [1]. They are defined as regions or layers with high refractive index in comparison with their surroundings. In waveguides, the light fields can be confined in very
small volumes, reaching relatively high intensities. The advantages of waveguidebased devices are twofolds: First, the diffraction-free light propagation enables beam
guidance and tailoring in chip-scale devices, which leads to a number of applications
in many areas; and second, the tight confinement of light fields brings out enhanced
features of bulk features in waveguides [2]. In 1996, Davis et al. reported on the first
femtosecond laser-written waveguides in a few family glasses [3], and numerous
subsequent works have been performed towards waveguide fabrication in various
transparent materials [4]. As of yet, direct femtosecond laser writing/inscription has
F. Chen (B)
School of Physics, State Key Laboratory of Crystal Materials, Shangdong University, Jinan
250100, China
e-mail: drfchen@sdu.edu.cn
J. R. V. de Aldana
Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada,
University of Salamanca, Salamanca 37008, Spain
© Springer Nature Switzerland AG 2020
A. Hu (ed.), Laser Micro-Nano-Manufacturing and 3D Microprinting, Springer Series
in Materials Science 309, https://doi.org/10.1007/978-3-030-59313-1_6
185