We propose the use of graphene as the electrode heater material for a polymer waveguide thermo-optic (TO) device. Because a graphene electrode can be buried in a polymer waveguide without introducing a significant loss to the transverse magnetic polarized light, we can do away with the buffer layer that is required in a conventional TO device to isolate the metal electrode heater from the waveguide and, hence, reduce the driving electric power of the device. To demonstrate the principle, we fabricate and compare two polymer waveguide TO mode switches based on the configuration of a balanced Mach–Zehnder interferometer, which are identical except that one uses a buried graphene electrode and the other uses an aluminum electrode deposited on the waveguide surface. Our experimental device that uses a graphene electrode has a switching power almost four times lower and also responds faster. The use of buried graphene electrodes is an effective approach to reducing the power consumption of TO devices.

By exploiting the polymer/silica hybrid and the air trench waveguide structures, we demonstrate a new type of low-power consuming and high-speed thermal-optic (TO) switch. Such a design provides an effective means to shorten the switching time of the TO switches, as well as to reduce the power consumption at the same time. This TO switch operated with less than 150 μs of switching time via a polymer/silica hybrid waveguide structure. Meanwhile, the power consumption was reduced to be 3.4 mW by introducing the air trench structure.

We propose a thermo-optic switch based on a symmetric directional coupler formed with two parallel identical two-mode waveguides, where the two modes in one waveguide can be simultaneously switched to the corresponding modes in the other waveguide. We design and fabricate such a device with polymer materials. Our fabricated device has a total length of 22.5 mm and operates at a switching power of 128 mW. The extinction ratios measured across the C-band are higher than ∼18 dB and ∼13 dB for the fundamental mode and the higher-order mode, respectively. The switching time is ∼1 ms. The performance of the device is insensitive to the polarization state of light. Our proposed mode-independent switch could find applications in reconfigurable mode-division-multiplexing transmission systems.

By exploiting the electro-absorption characteristic of graphene, we proposed and theoretically demonstrated an electro-absorption optical modulator (EOM) based on the graphene-buried polymer waveguides. By burying the graphene layers inside the polymer waveguide, acquiring a strong graphene-light interaction when the graphene layers buried in the center of core, which bring about an important change of the optical mode and effective mode index in the waveguide. The width of the graphene capacitor was also optimized to enhance the bandwidth of the device. Calculations show that the proposed EOM can realize 29 dB extinction ratio, 7 dB modulation depth and 42 GHz bandwidth with an 800 μm-long active region. The required switching voltage form its minimum to maximum absorption state is 1.6 V and 1.55 pJ/bit energy consumption can be achieved. The proposed modulator can remedy the lack of high-speed optical modulator on the passive polymer waveguide and have a potential application for polymer-based photonic integrated circuits.

We designed and fabricated a Mach–Zehnder interferometer (MZI) thermo-optic switch with an inverted triangular waveguide. The inverted triangular waveguide achieves a fundamental mode in a large waveguide dimension, which can reduce the coupling loss and increase the extinction ratio. The triangular waveguide-based switch was simulated and presented higher heating efficiency and lower power consumption than that of the traditional rectangular waveguide-based switch. Compared with the traditional rectangular waveguide-based device, the power consumption of the proposed device is reduced by 60%. Spacing photobleaching was introduced to fabricate the inverted triangular waveguide and adjust the refractive index to minimize the mode number. The insertion loss of the typical fabricated device with a 2 cm length is about 7.8 dB. The device shows an extinction ratio of ∼ 8.1 d B at 532 nm with a very low power consumption of 2.2 mW, and the switching rise time and fall time are 110 and 130 µs, respectively. The proposed single-mode waveguide and low-power-consumption optical switch have great potential applications in visible optical communication fields such as wavelength division multiplexing and mode-division multiplexing.

We propose a strip loaded amplifier employing SU-8 as the loaded waveguide and nanoparticles (NPs)-polymethyl methacrylate (PMMA) as the cladding layer. By leveraging the undoped SU-8 loaded waveguide, the polymer waveguide amplifier accomplished remarkably low transmission losses, reaching as low as 1.8 dB/cm at 1530 nm. We prepared NPs-PMMA nanocomposite by utilizing NaLu_0.1Y_0.7F₄: Er³⁺, Yb³⁺ @NaLuF₄ core-shell nanoparticles, which exhibited a significantly enhanced lifetime of 6.15 ms. An internal net gain of up to 17.7 dB was achieved on a strip loaded waveguide with a length as short as 0.5 cm when the on-chip pump power was 77 mW. Signal enhancement (SE) was measured at different wavelengths, revealing that the strip loaded waveguide exhibited broadband SE ranging from 1510 nm to 1570 nm, covering the C-band. To the best of our knowledge, this work has achieved the highest gain results reported thus far on a polymer matrix and provides an efficient method for optical amplification in passive devices on silicon and Si₃N₄ platforms, leveraging the ease of integration of polymer materials with diverse photonic platforms.