The low optical loss of G e 2 S b 2 S e 4 T e 1 (GSST) makes it a potential functional material for all-optical multilevel photonics memory devices that can operate in the optical telecommunication wavelength band. However, the same characteristic also restricted the tolerance of GSST phase change conditions using 1550 nm as an excitation light source. This work reports on the enhancement of GSST phase change condition tolerance using a graphene oxide (GO) intermediate layer on a polymer waveguide platform. The hybrid waveguide exhibits an insertion loss of around 1 dB and a maximum readout contrast of 25% between amorphous and crystalline states, with a step increase in readout contrast of around 5% per step. This work serves as a proof of concept for the implementation of a GSST–GO hybrid structure as an optical functional material in all-optical photonics memory applications.

The development of compact waveguide-based pulsed lasers has been of great interest in the past two decades. This is supported by the rapid development of two-dimensional (2D) materials saturable absorbers (SAs). In this paper, we integrate a large area monolayer molybdenum disulphide (MoS2) on a planarized silica optical waveguide and studied its performance as an SA. A single layer MoS2 film on polydimethylsiloxane substrate is mechanically transferred to the planarized optical waveguide. The single layer MoS2 can interact with the evanescent field of the waveguide core mode, thus achieving SA. The MoS2-coated waveguide is then integrated into an erbium-doped fibre laser cavity that operates in the telecommunication wavelength region. Q-switching is achieved with a repetition rate, pulse duration and maximum pulse energy of 22.5 kHz, 5.24 µs and 4.1 nJ, respectively at a pump power of 122.8 mW. The results show that 2D material thin films can be integrated onto a planarized optical waveguide to act as SAs. These findings show the potential of using 2D materials in developing compact, integrated waveguide pulsed laser sources.

No abstract

The nonlinear refractive index of large area monolayer molybdenum disulfide (MoS2) thin film at the 1,550[Formula: see text]nm wavelength band is determined using time-resolved z-scan technique. MoS2 exhibits positive nonlinear phase shift with a large nonlinear refractive index, [Formula: see text] value of [Formula: see text]. The obtained value is similar to the [Formula: see text] value of monolayer MoS2 film measured at 2.0[Formula: see text][Formula: see text]m, and is approximately five and seven orders of magnitude larger than silicon and common bulk dielectrics. The large [Formula: see text] indicates that MoS2 can be used as nonlinear refractive 2D material for photonics applications operating in the 1,550[Formula: see text]nm optical telecommunications wavelength band.