Efficient Optical Saturable Absorbers with Graphene on Polymer Waveguides for Femtosecond Laser Pulse Formation

Abstract

Photonic integrated circuits (PICs) are notable for their enhanced functionalities with material flexibilities to find applications in wearable high‐speed data management systems. Due to the miniaturized dimensions of PICs, the employment of a nanomaterial having significant optical nonlinearity is critical. Here, it is demonstrated that a polymer waveguide can be harmonized with nonlinear graphene to form ultrashort laser pulses. The graphene works as nonlinear saturable absorber on the polymer waveguide prepared with a perfluorinated acrylic resin. The evanescent field of a laser propagating through the waveguide interacts with graphene to induce intracavity intensity modulation for femtosecond‐scale pulse formation. The laser output is characterized quantitatively as the central wavelength, spectral width, repetition rate, extinction ratio, and pulse duration, which are 1553.32 nm, 10.21 nm, 4.18 MHz, 76.03 dB, and 874 fs, respectively. Stable operation is verified over 3 h.

Active and passive mode-locking of a laser using a graphene modulator on an SOI chip

“…Previous demonstrations have successfully employed graphene as a saturable absorber in passive mode-locked fibre lasers, either by placing a graphene sheet in the evanescent tail of a propagating mode in a fibre or by placing it onto a polymer waveguide [4][5][6]. Furthermore, active mode-locking using graphene has been achieved previously by placing graphene on top of a gold reflector separated by a HfOx gate dielectric, enabling electro-optic modulation when a voltage is applied between the mirror and the graphene sheet.…”

Directly Synthesized Graphene-Based Photonics and Optoelectronics Devices

“…Nevertheless, graphene is an ideal photonic and optoelectronic material due to the broadband optical properties [8][9][10][11][12][13][14]. The aforementioned characteristics forge the path for graphene to be a potential material for optoelectronic and photonic applications [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”