Wavelength beam combing of semiconductor lasers on a photonic integrated circuit (PIC) provides a simple, robust architecture to realize on-chip light sources for ultrabroadband wavelength division multiplexing (WDM) and multi-species trace gas spectroscopy. Several conventional device structures can be used to realize on-chip wavelength beam combing, such as multimode interferometers (MMIs), arrayed waveguide gratings (AWGs) and Mach-Zehnder interferometer (MZI) devices. However, the bandwidth of these beam combiners is quite limited, usually less than 100 nm. Besides, the insertion loss of these combiners is relatively high. On-chip wavelength beam combiners with a low insertion loss and a bandwidth of a few hundred of nanometers should be further developed. Here we demonstrate low-loss wavelength beam combing of two lasers with a wavelength spacing more than 1000 nm based on an adiabatic silicon nitride coupler. The transmission loss from the cross input to the bar output is around -1.2dB in the 1990 nm to the 2060 nm wavelength range. The transmission loss from the bar input to the bar output is -0.86dB in the 830 nm to the 870 nm wavelength range.
2-μm-wavelength-range spectroscopy and telecommunication applications could greatly benefit from the well-developed and highly scalable silicon photonics technology. However, the performance of silicon photonic components operating in this spectral range is still limited by the relatively large waveguide propagation loss. To address this pressing issue, we present an effective solution by harnessing the capabilities of the silicon nitride waveguide platform with its remarkable broadband transparency. In this work, we have successfully designed and demonstrated low-loss silicon nitride waveguides operating at the 2-μm wavelength, exhibiting an impressively low propagation loss of 1.07±0.04 dB/cm. Additionally, we have achieved the successful realization of high-Q microring resonator, exhibiting a record-high Q-factor of ~4.9×105 at the 2-μm wavelength.
Optical vortex beams carrying orbital angular momentum are being widely investigated for boosting the information capacity of communication systems by virtue of their unbounded state space for spatial mode division multiplexing or high-dimensional encoding. Vortex mode sorters are a critical component in such systems and a spiral transformation scheme working in the paraxial regime for vortex mode sorting has been proposed very recently to achieve high modal resolution with unity efficiency. Here we modify the spiral transformation scheme by developing a phase corrector in the nonparaxial regime, which is confirmed to have a more accurate phase-correcting function in implementing the spiral transformation and eventually lead to a better mode separation, especially in the case of a compact vortex mode sorter. Based on the above principle, a home-made compact vortex mode sorter is demonstrated by integrating the two phase elements implementing the spiral transformation onto the opposite sides of a thin quartz plate as flat diffractive optical elements, which achieves high-resolution and high-efficiency vortex mode sorting as expected. The modified optical spiral transformation and the compact design of vortex mode sorter based on this scheme therefore provide a much better tool for the effective mode separation, which can enable new applications in both classical and quantum information systems based on vortex modes.
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.