Integration of GaAs-based VCSEL array on SiN platform with HCG reflectors for WDM applications

Abstract

We present a GaAs-based VCSEL structure, BCB bonded to a Si 3 N 4 waveguide circuit, where one DBR is substituted by a free-standing Si 3 N 4 high-contrast-grating (HCG) reflector realized in the Si 3 N 4 waveguide layer. This design enables solutions for on-chip spectroscopic sensing, and the dense integration of 850-nm WDM data communication transmitters where individual channel wavelengths are set by varying the HCG parameters. RCWA shows that a 300nm-thick Si 3 N 4 HCG with 800nm period and 40% duty cycle reflects strongly (>99%) over a 75nm wavelength range around 850nm. A design with a standing-optical-field minimum at the III-V/airgap interface maximizes the HCG's influence on the VCSEL wavelength, allowing for a 15-nm-wide wavelength setting range with low threshold gain (<1000 cm -1 ).

A Review of Capabilities and Scope for Hybrid Integration Offered by Silicon-Nitride-Based Photonic Integrated Circuits

“…As the most obvious material advantage compared with that of Si-, SiN-coupled lasers can extend working wavelengths down to the visible-NIR wavelength range below 1100 nm, where virtual reality (VR)/augmented reality (AR), high-density optical storage, short-reach communication, and quantum technologies play important roles (Figure 9) [233][234][235]. An example of the benefits offered by integration in SiN was demonstrated by Kumari and colleagues, who employed a SiN-based high-index-contrast subwavelength grating (HCG) to substitute one of the distributed Bragg reflectors (DBRs) of a GaAs VCSEL working at 850 nm, via adhesive die bonding [236]. The grating structure not only worked as a cavity mirror, but it also guided light into the horizontal direction (perpendicular to the DBR stacks) out of the cavity.…”

Silicon-integrated short-wavelength hybrid-cavity VCSEL

“…In addition, a silicon nitride waveguide can be connected to the HCG for in-plane emission, which has been demonstrated for long-wavelength VCSELs [7,13,14]. Together with an integrated wavelength multiplexer, this would enable the fabrication of fully integrated high speed and high efficiency shortwavelength transmitters for WDM optical interconnects [15].…”

Design of GaAs microcavity on SiN waveguide for efficient single-photon generation by resonant excitation

“…A promising way to solve this problem is heterogeneous and hybrid integration of active components [9,[13][14][15][16][17]. Various components, including light sources [18][19][20][21][22][23][24], modulators [25][26][27][28][29], and detectors [18], have been demonstrated to overcome the problem on SiN. In spite of aforementioned advancements, it is still challenging to have an ideal single-photon source that deterministically generate single photons for information processing with discrete variables, instead of probabilistic single-photon generation from nonlinear processes in SiN.…”