T-rail electrodes has emerged as a promising candidate for increasing the electro-optical modulator(EOM) bandwidth, compared to traditional travelling wave electrodes. We demonstrate an equivalent model of thin film lithium niobate (TFLN) Mach-Zehnder modulators with T-rail electrodes, utilizing the distributed capacitance and conformal mapping techniques to calculate the microwave refractive index, RF characteristic impedance, microwave loss. The validity of the values extracted from the equivalent circuit model is confirmed by their agreement with finite element method (FEM) simulations. We analyze various influential parameters affecting modulator performance to enhance design efficiency and achieve a 3dB bandwidth of approximately 120 GHz.
The rapid advancement in integrated optics offers a viable approach for further reducing the size and weight of interferometric fiber optic gyroscopes (IFOGs) by integrating optoelectronic transceiver modules. This paper proposes a design for an integrated optoelectronic transceiver module for IFOG, incorporating a superluminescent laser diode (SLD) light source, beam splitter, photodetector (PD), and transimpedance amplifier (TIA). Through optimization of the optical path and structural design, the emitted optical power from the fiber pigtail exceeded 1 mW under a 100 mA drive current, with the closed-loop overall loss measured at approximately 13 dB. An integrated IFOG test system was developed, and its zero-bias stability was measured at 0.3755 °/h, meeting the requirements of tactical-grade systems. The transceiver shows substantial potential to streamline the IFOG assembly process and reduce assembly costs, a critical factor in the miniaturization of IFOGs.
A three-section dual-transverse mode hybrid resonant laser has been successfully developed on the InP platform, utilizing a 2D sampling grating. This laser comprises an active section with a π phase-shifted anti-symmetric Bragg grating (π-ASBG) and two passive sections with uniform Bragg gratings (UBGs). With this design, it enables the simultaneous and stable emission of both the fundamental transverse electric mode (TE0) and the first-order transverse electric mode (TE1). The physical mechanism of dual-transverse mode hybrid resonance in the cavity of a semiconductor laser is analyzed, based on the coupled-mode theory. The experimental results indicate that the laser consistently maintains an output wavelength of 1549 nm, achieving side-mode suppression ratios (SMSR) of 38 dBand30 dB, respectively, under the emission of the TE0 mode and the TE1 mode. Therefore, as the transverse mode tunable light source, the laser may benefit the future mode division multiplexing (MDM) systems for more reconfigurability and flexibility.
A 16-channel optical transmitter chip with a digital transmission capacity up to 1.6 Tb/s has been demonstrated. In this chip, a 16-wavelength III–V DFB laser array (MLA), a silicon Mach-Zehnder interferometer (MZI) modulator array and a 16-channel fiber array are hybrid integrated by photonic wire bonding (PWB) technique. The MLA based on reconstruction-equivalent-chirp (REC) technique proves a good wavelength spacing uniformity of all wavelengths. Each unit laser with 1.2 mm cavity length in the MLA exhibits good single-longitudinal-mode operation with the output power over 18 dBm at an injection current of 300 mA. Spectral measurements show the channels coincide well with the designed 200 GHz spacing, with wavelength deviations within a range of ±0.2 nm. Based on PWB technique, three chips mentioned above are integrated optically on one Wu-Cu substrate as a 16-channel optical transmitter. The largest output power of optical transmitter is 1.5 mW and all channels still keep good single mode outputs after PWB integration. The tested modulation speed of each channel is up to 100 Gb/s, which implies the total transmission capacity of this device is 1.6 Tb/s.
KEYWORDS: Waveguides, Distributed feedback semiconductor lasers, Design and modelling, Continuous wave operation, High power lasers, Laser development, Semiconductor lasers, Optical simulations, Near field
In this paper, we designed a Slab Coupled Optical Waveguide (SCOW) DFB semiconductor laser around 1550 nm with increased output optical power and single mode operation. Under the assumption of idea heat dissipation, we simulate the performances of the designed DFB laser using PICs3D software. A Continuous-Wave (CW) output power of 1.03 W is obtained under the bias current of 2.7A, with the slope efficiency of 0.402 W/A. Because of the asymmetric Separated Confinement Heterostructure (SCH) and the passive waveguide structure, the mode profile is expanded. Then, single mode outputs with near-field mode spot size of 5 μm×5 μm and the Full Width at Half Maximum (FWHM) far-field divergence angle is as low as 9.2°×16.2°. Therefore, the designed 1550 nm high power DFB semiconductor laser has potential applications in the fields such as silicon-based photonics integration, Free Space Optical (FSO) communication and light detection and ranging (LiDAR) systems.
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