Monolithic Add–Drop Multiplexers in Fused Silica Fabricated by Femtosecond Laser Direct Writing

Abstract

The fabrication of optical add-drop multiplexers in fused silica is demonstrated, for the first time to our knowledge, using the femtosecond laser direct writing technique. To achieve this, a Mach-Zehnder interferometer configuration was used for the signal routing by the implementation of 3-dB directional couplers, along with Bragg grating waveguides for wavelength selectivity. The fabrication of all individual devices required was optimized. The behavior of the fabricated add-drop multiplexer was characterized at around 1550 nm, where a 3-dB bandwidth of 0.19 ± 0.01 nm was obtained along with an intrachannel and adjacent interchannel crosstalk of -30 and -20 dB at Δλ = ± 0.75 nm, respectively. This study shows that such complex devices can be manufactured by femtosecond laser direct writing, with future improvements being discussed.Index Terms-Add-drop multiplexer, femtosecond laser, integrated optics, laser materials-processing applications, optical device fabrication, wavelength division multiplexing.

Temperature compensated strain sensor in fused silica by femtosecond laser inscription

“…The fabrication technology employed for the realization of the sensor is a combination of femtosecond laser direct writing (FLDW) [20][21][22][23][24][25][26][27][28] and femtosecond laser irradiation followed by chemical etching (FLICE). [29][30][31][32][33][34][35] Mostly these technologies have been demonstrated separately, though a few papers combine them 36,37 Firstly, all structures (waveguides, Bragg gratings, contours of V-grooves and cantilever) are formed in a single laser exposure step.…”

Photonic circuits written by femtosecond laser in glass: improved fabrication and recent progress in photonic devices

“…8(g). 115 To this end, two DCs with a symmetrical geographical layout were used in a Mach-Zehnder interferometer configuration for the signal routing, and the inserted Bragg grating WGs between the DCs worked for wavelength selectivity. In principle, the input signal is split equally into two WGs by the first DC, which is then guided to two identical Bragg grating WGs.…”

Study on fs-laser machining of optical waveguides and cavities in ULE® glass

“…The use of Zerodur ® or ULE ® in interferometry is usually done through assembly of free-space optics on optical benches, with these modules being either entirely or partially made from the former materials [6,7]. Laser direct writing and machining of them is seldom considered, despite its advantages on 3D integration, multiplexing of optical channels and combination of integrated optics with microfluidics [8][9][10][11]. This microfabrication technique relies on energy transferred from the pulsed laser beam into the irradiated material through non-linear absorption processes, with subsequent relaxation and modification of the laser-modified volume that is confined to the inner part of the focal volume [12,13].…”