A low-loss LNOI edge coupler fabricated on 4-inch wafer with deep ultraviolet lithography was demonstrated. The coupler was fabricated on LNOI with 600 nm thin-film lithium-niobate by 180nm lithography and ICP etch process. The 600nm thin-film lithium-niobate was etched for three times to achieve the coupler with tri-layer structure and narrow taper tips of below 150 nm. The fiber to chip coupling loss is 0.84 dB and 1.3 dB per facet for TE light at 1550 nm, when coupled with lensed fibers, which have 4 μm and 3.5 μm mode field diameter, respectively. Furthermore, the coupling loss is less than 1 dB per facet in the wavelength range between 1520 to 1560 nm.
One of the key challenges for realizing large-scale quantum communication in installed fiber networks is to establish communication links between multiple users in a scalable and robust way. Quantum networks based on DWDM quantum correlation utilizing broadband entangled photon pair source could be the solution. Among many integrated photon source techniques, AlGaAs Bragg reflection waveguid (BRW), with its extremely high material χ(2) and negligible birefringence, can produce high brightness, wide bandwidth, post selection free polarization entangled photon pairs. In a scenario of entangled photon and classical light co-fiber transmitting, noise from the classical light could degrade the entanglement. In this paper. we designed and fabricated a Bragg reflection waveguide (BRW) AlGaAs/GaAs chip with high modal overlap to directly generate broadband polarization entanglement, and employed for demonstrate a fully connected three-user noisy network by multiplexing 3 pairings of DWMD channels, each pairing established a quantum communication link between any possible two users. Several causes of noise from chip fluorescence to co-fiber classical light, and their impacts on bit error rate (BER) were analyzed.
In this paper, we demonstrate a high-Q LNOI microdisk coupling with a silicon nitride (Si3N4) optical waveguide. Its resonance characteristic can be turned by a thermistor on the microdisk resonator. The LNOI microdisk resonator is fabricated by inductively coupled plasma-reactive ion etching (ICP-RIE). Its sidewall is further smoothed by employing chemical mechanical polishing (CMP) to improve the quality factor (Q-factor). The LNOI/Si3N4 heterogeneous integrated resonator shows a Q-factor of 2.58 × 105, and a wavelength tunability of ~14.5 pm/W.
As one of the most promising optical nonlinear material, AlGaAs has several advantages such as high second and third order nonlinear coefficients, freedom of material engineering, potential of full quantum photonic system on chip (SOC) including pump laser. In this paper, we estimate the photon pair generation and second harmonic generation (SHG) by an AlGaAs Bragg Rreflection waveguide (BRW) which design and manufactured on GaAs substrate.
GaAs Schottky barrier diode (SBD) based terahertz mixer and frequency multiplier represent one of the most important method for terahertz signal emitting and receiving from 0.5THz to 5THz. Compared with original GaAs substrate, quartz using as GaAs SBD circuit base could suppress transmission loss and high order transmission mode on chip, benefits from low dielectric constant of quartz. In this paper, GaAs SBD was integrated on quartz substrate using transfer printing technique, which could achieve membrane device transfer and low cost high output of original GaAs wafer.
InGaAs schottky diode with the property of low barrier height, simple material structure, and mature InP based integrated process, has become one of the major techniques for zero biased terahertz detector. As a thorough study from device to circuit, a “T” shape anode designed InGaAs SBD with ft over 3THz was presented, a novel device equivalent circuit model for InGaAs SBD was established, and a 75-110GHz W band zero biased detector circuit was design and fabricated, with the peak voltage responsivity of 25880V/W, indicating great potential for zero biased terahertz detection.
A flat band-pass photonic filter is experimentally demonstrated on a silicon-on-insulator (SOI) substrate. The filter is composed of a micro-ring resonator assisted with an asymmetric Mach-Zehnder interferometer (MZI). By thermal tuning the ring, the device achieves a rapid roll-off on the band edges, a wide 3-dB bandwidth of 0.95 nm and a low crosstalk of 14 dB. The filter can be used in the WDM network and integrated microwave photonic signal processing.
The 3ω method has proven very useful for determining the thermal conductivity of the film and the substrate. According to the principle of 3ω method, a thermal conductivity test platform was built and the SiO2 film was measurement to verify the accuracy of experimental system. In this work, the different thicknesses of SiN films were grown by PECVD and the thermal conductivity was measured by 3ω method. In order to improve the accuracy of the thermal conductivity measurement, the influence of film-substrate interfacial thermal resistance was introduced into the heat transfer model. The experimental results show that the thermal conductivity of SiN films increases with increasing thickness, and the correction thermal conductivity is obviously higher than the original value.
We experimentally demonstrate high-speed InGaAs/InP drift-enhanced photodetectors with different diameters and absorbing layer thicknesses. For photodiodes with optical window diameters of 10 μm, 7 μm and 5 μm, we have achieved 3-dB bandwidths of 32GHz, 40 GHz and over 40 GHz from a 500-nm-thickness intrinsic InGaAs absorption layer and 30 GHz, 34 GHz and 36 GHz bandwidths from a 700-nm-thickness absorption layer, respectively. The measured values are in good agreement with the theoretical calculations.
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