We propose a simple and effective model to properly design the monolithically integrated tunable optical transmitter based on the traveling wave Mach-Zehnder modulator (TW-MZM) and V-cavity laser (VCL). Firstly, the integrated structure of TW-MZM and VCL is presented. Then we put forward a TW-MZM model to design and improve the performance of the electro-optic (EO) modulation bandwidth of the optical transmitter. By changing the structural parameters of the optical waveguide and the traveling wave electrodes, we reduce the microwave transmission loss from 3 mm-1 to 0.6 mm-1 at 20 GHz and thus increase the theoretical electro-optic response from 13.5 GHz to 52.8 GHz. Due to the high modulation efficiency from the Quantum Confined Stark Effect (QCSE) in quantum wells, the traveling wave modulator is very compact with a length of only 600 μm.
An on-chip TE-pass polarizer working near 850nm band is designed and fabricated on silicon nitride platform. The structure is very simple, using a straight silicon nitride waveguide separated from a metal strip by a low index silicon oxide spacer layer. By optimizing the thickness of the spacer layer, the metal strip introduces more loss for TM mode than TE mode. The measured extinction ratio of the fabricated device is around 20dB over a 16nm wavelength range from 837nm to 853nm for a 3mm-long polarizer.
A tunable V-cavity laser based on half-wave multimode interference reflector (MIR-VCL) which operates in O-band is purposed and experimentally demonstrated. The superior side mode suppression ratio (SMSR) is achieved by the halfwave MIR, which is analyzed through the theory of multimode interference coupler. The laser is fabricated on the five quantum wells (QWs) InGaAlAs/InP wafer whose PL peak is about 1300 nm and has a compact device size of 500 µm × 350 µm. With the injection current on the gain electrode and short cavity electrode fixed, 27 channels with a spacing of about 100 GHz are obtained by tuning the injection current on the long cavity electrode. Experimental results show that among the whole tuning range, the SMSR ranges from 35 dB to 41.5 dB. By controlling the injection current on gain electrode and the TEC temperature, 51-channel wavelength tuning from 1288 nm to 1318 nm is obtained. The laser reaches its threshold when the total injection current is 65 mA. The tunable MIR-VCL in O-band has good potential for applications in 5G front-haul and datacenter networks.
The monolithic integration of a tunable V-coupled-cavity laser based on half-wave multimode interference reflector (MIR-VCL) with a travelling-wave Mach-Zehnder modulator (TW-MZM) on generic InP foundry platform is present in this paper. The formation mechanism of pi-coupling-phase difference and the contradiction among loss, optimal coupling phase difference and optimal coupling coefficients of half-wave coupler are analyzed. Single electrode tuning of 11 channels of about 7.3nm wavelength range is obtained, which is determined by the cavity length and the 10% cavity length difference. Among the whole wavelength tuning range, the side mode suppression ratios (SMSRs) are all above 35dB and the typical one is about 42dB. The Mach-Zehnder modulator with optimized travelling wave electrode is integrated with the MIR-VCL by two two-ports MIRs, which could provide optical feedback for laser and CW light for MZM in the meantime. The monolithic integrated transmitter on generic InP platform is free of complicated fabrication process of grating structure and has good potential for cost effective applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.