Sifotonics Technologies Co., Ltd.

Sifotonics Technologies (beijing) Co., Ltd.

Pengfei Cai

Dong Pan

Mengyuan Huang

Ching-yin Hong

Wang Chen

Su Li

Liangbo Wang

Tuo Shi

Tzung-I Su

Yadong Liu

Zhou Fang

Wei Lin

Ning Zhang

Nai Zhang

Rangchen Yu

Fan Qi

Chang Liu

Bin Shi

Changhua Chen

Yanwu Zhang

Tzung I Su

Siying Liu

Naichuan Zhang

The present invention provides a normal-incident photodiode structure with a dark current self-compensation function, including a photosensitive photodiode and a compensating photodiode, where a photosensitive surface of the compensating photodiode is provided with a light-blocking layer, and dark currents of the photosensitive photodiode and the compensating photodiode are equal. According to the present invention, the dark current self-compensation function may be implemented at a chip level without an external circuit and an operational amplifier; the normal-incident photodiode structure according to the present invention has the photosensitive photodiode and the compensating photodiode, and the compensating photodiode may counteract the dark current of the photosensitive photodiode during operation, thus reducing noise caused by the dark current of the photosensitive photodiode; and bias voltages of the photosensitive photodiode and the compensating photodiode according to the present invention are controlled separately, and thus may be applied to more usage scenarios.

Normal-incident photodiode structure with dark current self-compensation function

The present invention provides a silicon-based integrated optical chip integrating a silicon-based optical modulator and a germanium-silicon detector and a preparation method thereof. A position and dimension of a silicon nitride waveguide are defined by a slot formed by using an etching process, then surplus silicon nitride is removed by means of chemico-mechanical polishing, and an optical waveguide is formed by the silicon nitride in the slot. Therefore, the preparation of the silicon nitride waveguide according to the present invention can be compatible with a process for preparing the silicon-based integrated optical chip including the silicon-based optical modulator and the germanium-silicon detector, and a distance between the silicon nitride waveguide and the silicon waveguide may be controlled flexibly, so that controllable coupling strength and coupling loss between the silicon waveguide and the silicon nitride waveguide are implemented; and the silicon waveguide at a bottom layer and the silicon nitride waveguide at an upper layer may be used to design in combination various passive devices with better performance, for example, a coupler with lower coupling loss and a waveguide with lower transmission loss.

Silicon-based integrated optical chip

The present disclosure provides a coherent light receiving optical device. It includes: an optical switch group, each optical switch thereof is configured to switch between two different preset bands and output two signal lights or two oscillation lights corresponding to the two different preset bands; a 1×2 power beam splitter group, each 1×2 power beam splitter thereof is configured to split one of the two oscillation lights into two split oscillation lights; an optical hybrid group, each optical hybrid thereof is configured to mix the one split oscillation light from an oscillation path with one signal light from a signal path in the same preset band, to output a mixed light; a detector group, each detector thereof is configured to convert the mixed lights of two different preset bands in the mixed lights into photocurrent in the same detector, so as to multiplex the detector.

Coherent light receiving optical device

Various embodiments of a monolithic transceiver are described, which may be fabricated on a semiconductor substrate. The monolithic transceiver includes a coherent receiver module (CRM), a coherent transmitter module (CTM), and a local oscillation splitter to feed a local oscillation to the CRM and the CTM with a tunable power ratio. The monolithic transceiver provides tunable responsivity by employing photodiodes for opto-electrical conversion. The monolithic transceiver also employs a polarization beam rotator-splitter (PBRS) and a polarization beam rotator-combiner (PBRC) for supporting modulation schemes including polarization multiplexed quadrature amplitude modulation (PM-QAM) and polarization multiplexed quadrature phase shift keying (PM-QPSK).

Monolithic integrated coherent transceiver

Various embodiments of a coplanar waveguide (CPW) transmission line as well as a silicon-based electro-optic (E-O) modulator comprising the CPW transmission line are described. The CPW transmission line has a curved or winding shape. The silicon-based E-O modulator includes a rib optical waveguide, a beam splitter, a beam combiner, and a CPW transmission line that exhibits the winding shape. At least one of the two optical arms of the rib optical waveguide alternately and periodically extends through a first groove and a second groove of the CPW transmission line. The plurality of active sections of the rib optical waveguide are evenly distributed on both sides of the CPW transmission line to suppress undesired transmission modes. An increased length of transmission path of the rib optical waveguide is also avoided or minimized, thereby reducing the transmission speed mismatch of the E-O modulator, which is essential for achieving high-speed operation.

Coplanar waveguide transmission line and silicon-based electro-optic modulator comprising the same

Various embodiments of a monolithic transceiver are described, which may be fabricated on a semiconductor substrate. The monolithic transceiver includes a coherent receiver module (CRM), a coherent transmitter module (CTM), and a local oscillation splitter to feed a local oscillation to the CRM and the CTM with a tunable power ratio. The monolithic transceiver provides tunable responsivity by employing avalanche photodiodes (APDs) for opto-electrical conversion. The monolithic transceiver also employs a polarization beam rotator-splitter (PBRS) and a polarization beam rotator-combiner (PBRC) for supporting modulation schemes including polarization multiplexed quadrature amplitude modulation (PM-QAM) and polarization multiplexed quadrature phase shift keying (PM-QPSK).

Various embodiments of a monolithic electro-optical (E-O) modulator are described. The monolithic E-O modulator includes an active region comprising a plurality of p-n junction diodes, as well as a modulation electrode and a bias electrode that extend through the active region. The monolithic E-O modulator further includes a resistor-capacitor-bias-capacitor (RCBC) electrode structure configured to receive an electrical modulation signal, a direct-current (DC) bias voltage and a power supply voltage. Specifically, the RCBC electrode structure includes a resistor coupled to the modulation electrode and two capacitors each coupled to a respective end of the bias electrode. Beneficially, the RCBC electrode structure enables the p-n junction diodes to be biased independently from a DC level of the electrical modulation signal.

Monolithic electro-optical modulator having RCBC electrode structure

Various embodiments of a monolithic electro-optical (E-O) modulator are described herein. The monolithic E-O modulator may include a phase shifter having a suspended structure. The suspended structure may be realized by partially or completely removing silicon material underneath the active area of the phase shifter to form a void in the bulk silicon substrate supporting the phase shifter. The suspended structure may be utilized to result in a lower radio-frequency loss and an effective group refractive index of the phase shifter that is closer to the refractive index of silicon waveguides or optical fibers, both advantageous to enhancing the performance of the E-O modulator such as a higher operating bandwidth.

Monolithic electro-optical modulator having suspended structure

Various embodiments of a fully integrated avalanche photodiode receiver and manufacturing method thereof are described herein. A photonic device includes a silicon-on-insulator (SOI) substrate with a buried oxide (BOX) layer therein, an avalanche photodiode integrated with the SOI substrate, a capacitor integrated with the SOI substrate, a resistor integrated with the SOI substrate, and silicon passive waveguides as well as bonding pads integrated with the SOI substrate.

Fully integrated avalanche photodiode receiver

Various embodiments of a compensated photonic device structure and fabrication method thereof are described herein. In one aspect, a photonic device may include a substrate and a functional layer disposed on the substrate. The substrate may be made of a first material and the functional layer may be made of a second material that is different from the first material. The photonic device may also include a compensation region formed at an interface region between the substrate and the functional layer. The compensation region may be doped with compensation dopants such that a first carrier concentration around the interface region of function layer is reduced and a second carrier concentration in a bulk region of functional layer is reduced.

Compensated photonic device structure and fabrication method thereof

Various embodiments of a compensated photonic device structure and fabrication method thereof are described herein. A photonic device may include a silicon-on-insulator (SOI) substrate with a buried oxide (BOX) layer therein, a Si waveguide and an n-type contact layer formed on the BOX layer, a Si multiplication layer disposed on the n-type contact layer, a p-type Si charge layer disposed on the Si multiplication layer, a germanium (Ge) absorption layer disposed on the p-type Si charge layer, a p-type contact layer disposed on the Ge absorption layer, and a metal layer disposed on the p-type contact layer. A compensated region may be formed between the p-type Si charge layer and the Ge absorption layer with a portion of the compensated region in the p-type Si charge layer and another portion of the compensated region in the Ge absorption layer.

Avalanche photodiodes (APDs) having at least one top stressor layer disposed on a germanium (Ge) absorption layer are described herein. The top stressor layer can increase the tensile strain of the Ge absorption layer, thus extending the absorption of APDs to longer wavelengths beyond 1550 nm. In one embodiment, the top stressor layer has a four-layer structure, including an amorphous silicon (Si) layer disposed on the Ge absorption layer; a first silicon dioxide (SiO) layer disposed on the amorphous Si layer, a silicon nitride (SiN) layer disposed on the first SiOlayer, and a second SiOlayer disposed on the SiN layer. The Ge absorption layer can be further doped by p-type dopants. The doping concentration of p-type dopants is controlled such that a graded doping profile is formed within the Ge absorption layer to decrease the dark currents in APDs.

High performance GeSi avalanche photodiode operating beyond Ge bandgap limits

Various embodiments of a novel structure of a Ge/Si avalanche photodiode with an integrated heater, as well as a fabrication method thereof, are provided. In one aspect, a doped region is formed either on the top silicon layer or the silicon substrate layer to function as a resistor. When the environmental temperature decreases to a certain point, a temperature control loop will be automatically triggered and a proper bias is applied along the heater, thus the temperature of the junction region of a Ge/Si avalanche photodiode is kept within an optimized range to maintain high sensitivity of the avalanche photodiode and low bit-error rate level.

Ge/Si avalanche photodiode with integrated heater and fabrication method thereof

A high-speed germanium on silicon (Ge/Si) avalanche photodiode may include a substrate layer, a bottom contact layer disposed on the substrate layer, a buffer layer disposed on the bottom contact layer, an electric field control layer disposed on the buffer layer, an avalanche layer disposed on the electric field control layer, a charge layer disposed on the avalanche layer, an absorption layer disposed on the charge layer, and a top contact layer disposed on the absorption layer. The electric field contact layer may be configured to control an electric field in the avalanche layer.

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Beijing, China

Pengfei Cai