A 32×4 optical switch based on high-index doped silica glass (HDSG) is proposed for reconfigurable optical add-drop multiplexer (ROADM) applications. The switch is designed to route any of the 32 inputs to the express ports or drop any channels from the 32 inputs to the target 4 drop ports or add any of the 4 ports to any of the 32 express channels. The switch comprises 188 Mach-Zehnder Interferometer (MZI) type switch elements, 88 optical vias for the 44 optical bridges, and 618 waveguide-waveguide crossings with three-dimensional (3D) structures. At 1550 nm, the fiber-to-fiber loss for each express channel is below 2 dB, and across the C and L bands, below 3 dB. For each input channel to all 4 drop/add channels at 1550 nm, the loss is less than 3.5 dB and less than 5 dB across the C and L bands. The polarization-dependent loss (PDL) for all express and input channels to the 4 drop/add channels is below 0.3 dB over the C band, and the crosstalk is under -50 dB for both the C and L bands. The switch is fabricated using a CMOS-compatible HDSG platform, which offers a moderate index contrast of 10%, enabling significant device size reduction compared to conventional low-index PLCs while maintaining superior fiber coupling efficiency and fabrication sensitivity. The switch is packaged with 128-channel single-mode fiber (SMF) array and a ceramic substrate. The device is tested with a 100 GHz DWDM grid, and the fiber-to-fiber losses for 32 channels in the express case are below 2 dB, and in drop cases, the losses are lower than 3.5 dB. The PDL of the device is below 0.3 dB in the C band, and the crosstalk of all 32 input channels is less than -50 dB for express cases and -40 dB for drop/add cases. Thirty-two variable optical attenuators (VOAs) are also incorporated, and the PDL is lower than 1 dB within the C band at 10 dB VOA attenuation. The switch demonstrates low insertion loss (IL), low PDL, and low crosstalk, making it suitable for ROADM applications. The device is designed to be compact, robust, and cost-effective, with a moderate index contrast that balances fiber coupling loss, propagation loss, and PDL. The switch is fabricated using a 3D integration process, enabling ultra-low loss crossings (below 0.003 dB) by distributing waveguide crossings in two separate bus layers. The device is also polarization-insensitive, allowing for low PDLA 32×4 optical switch based on high-index doped silica glass (HDSG) is proposed for reconfigurable optical add-drop multiplexer (ROADM) applications. The switch is designed to route any of the 32 inputs to the express ports or drop any channels from the 32 inputs to the target 4 drop ports or add any of the 4 ports to any of the 32 express channels. The switch comprises 188 Mach-Zehnder Interferometer (MZI) type switch elements, 88 optical vias for the 44 optical bridges, and 618 waveguide-waveguide crossings with three-dimensional (3D) structures. At 1550 nm, the fiber-to-fiber loss for each express channel is below 2 dB, and across the C and L bands, below 3 dB. For each input channel to all 4 drop/add channels at 1550 nm, the loss is less than 3.5 dB and less than 5 dB across the C and L bands. The polarization-dependent loss (PDL) for all express and input channels to the 4 drop/add channels is below 0.3 dB over the C band, and the crosstalk is under -50 dB for both the C and L bands. The switch is fabricated using a CMOS-compatible HDSG platform, which offers a moderate index contrast of 10%, enabling significant device size reduction compared to conventional low-index PLCs while maintaining superior fiber coupling efficiency and fabrication sensitivity. The switch is packaged with 128-channel single-mode fiber (SMF) array and a ceramic substrate. The device is tested with a 100 GHz DWDM grid, and the fiber-to-fiber losses for 32 channels in the express case are below 2 dB, and in drop cases, the losses are lower than 3.5 dB. The PDL of the device is below 0.3 dB in the C band, and the crosstalk of all 32 input channels is less than -50 dB for express cases and -40 dB for drop/add cases. Thirty-two variable optical attenuators (VOAs) are also incorporated, and the PDL is lower than 1 dB within the C band at 10 dB VOA attenuation. The switch demonstrates low insertion loss (IL), low PDL, and low crosstalk, making it suitable for ROADM applications. The device is designed to be compact, robust, and cost-effective, with a moderate index contrast that balances fiber coupling loss, propagation loss, and PDL. The switch is fabricated using a 3D integration process, enabling ultra-low loss crossings (below 0.003 dB) by distributing waveguide crossings in two separate bus layers. The device is also polarization-insensitive, allowing for low PDL