CN-115826229-B - Polarization insensitive waveguide device design method

CN115826229BCN 115826229 BCN115826229 BCN 115826229BCN-115826229-B

Abstract

The invention discloses a design method of a polarization insensitive waveguide device, which comprises the steps of arranging a photonic integrated material platform, arranging a functional waveguide device or a system for optical signal processing on the photonic integrated material platform, arranging an input end conversion device in front of the functional waveguide device or the system, and arranging an output end conversion device behind the functional waveguide device or the system. The design method reduces the design difficulty, does not introduce extra power consumption and on-chip loss, remarkably improves the system integration level, and provides a new scheme for realizing polarization insensitive waveguide devices and systems.

Inventors

CHU TAO
WU YATING

Assignees

浙江大学

Dates

Publication Date: 20260512
Application Date: 20221209

Claims (4)

1. A method of designing a polarization insensitive waveguide device comprising the steps of: 1) Setting a photon integrated material platform; the photon integrated material platform is a platform with a double refraction effect; 2) Providing a functional waveguide device or system on the photonic integrated material platform; 3) Setting the functional waveguide device or an input end conversion device in front of the system; The input end conversion device is connected with the input waveguide and the functional waveguide device or the front end of the system, and can convert the orthogonal polarization mode into different modes of a single polarization state; The different modes of the single polarization state are combinations of any two or more modes of the single polarization state, the combinations of any two or more modes of the single polarization state comprise combinations of two or more higher-order modes or combinations of a basic mode and one or more higher-order modes, and the higher-order modes are modes with higher orders than the basic mode; 4) And arranging the functional waveguide device or an output end conversion device after the system.
2. The method for designing a polarization insensitive waveguide device according to claim 1, wherein in step 4), the output end conversion device is connected to the functional waveguide device or the system back end and the output waveguide, the output end conversion device is an input end conversion device placed reversely, and the output end conversion device converts different modes of a single polarization state back to corresponding orthogonal polarization state modes according to the reversibility of the optical path.
3. The method of designing a polarization insensitive waveguide device according to claim 1, wherein in step 2), the functional waveguide device or system is used for optical signal processing and is capable of operating normally in different modes of a single polarization state as defined in claim 1.
4. The method of designing a polarization insensitive waveguide device according to claim 1, wherein when the functional waveguide device in step 2) is an optical switch or modulator, the photonic integrated material platform is a thin film lithium niobate platform, and the optical switch or modulator is a Mach-Zehnder interferometric structure comprising a beam splitter and a phase shift arm, both of which are suitable for 、 A mode; An input conversion device is arranged at the front end of the optical switch or modulator, will be Mode conversion to Mode without change A mode; 、 the two modes are switched or modulated by a functional waveguide device; An output end conversion device is arranged at the rear end of the optical switch or modulator, will be Mode switch back Mode, unchanged Thereby a polarization insensitive optical switch or modulator is obtained.

Description

Polarization insensitive waveguide device design method Technical Field The invention relates to the technical field of semiconductors, in particular to a design method of a polarization insensitive waveguide device and a system. Background Photon integration, which uses photons as carriers for information transmission, has the characteristics of low delay, low power consumption, large bandwidth and the like, and has great development potential in data communication, thereby causing wide research of domestic and foreign scientific researchers. The photonic integrated platform may be classified into indium phosphide-based, sapphire-based, silicon-based, and the like, depending on the substrate. In order to increase the limitation of the waveguide to the optical mode and improve the integration level, a certain refractive index difference needs to be met between the core layer and the cladding layer materials, and the difference of stresses in different directions causes that most platforms show strong birefringence effect and obvious polarization correlation, and typical devices such as a directional coupler, a modulator and the like are often only suitable for one polarization, otherwise, the performance of the device is seriously deteriorated. However, in the optical fiber communication process, the transmitted optical signal exhibits random dynamic changes due to bending of the ordinary single-mode optical fiber and changes of the surrounding environment, rather than only a single polarization state. The polarization-maintaining fiber can maintain stability of a single polarization state, but is incompatible with the existing infrastructure in long-distance transmission, and the operation cost is greatly increased. Thus, to accommodate the random polarization state of the optical signal in the optical fiber, and to receive complete information, polarization insensitive functional devices or systems are often designed on the mainstream photonic integrated platforms, and mainly include the following schemes. The first scheme is to adopt means such as a symmetrical waveguide structure, stress engineering and the like to realize an isotropic waveguide, and design a polarization insensitive waveguide device on the basis of the isotropic waveguide, but the waveguide structure is usually weak in constraint of an optical mode and low in integration level, so that monolithic integration with a microelectronic device is difficult to realize, and the stress control increases the operation difficulty. The second scheme is polarization diversity, which uses devices with polarization separation or polarization separation rotation functions, such as a Polarization Beam Splitter (PBS), a Polarization Separation Rotator (PSR), a two-dimensional grating, and the like, to orthogonally split the random polarization state coupled from the optical fiber into two paths or further rotate the orthogonal polarization state into two paths of homogeneous polarization states, and then respectively pass through a set of functional waveguide devices or systems, and finally pass through the photonic devices with polarization separation or polarization separation rotation functions placed in opposite directions to realize the beam combination of the two paths of light. The technical route of the scheme is simple, but the chip area is at least doubled due to the addition of two sets of functional waveguide devices or systems, and the increase of the number of the electrodes also increases the difficulty of electric packaging and driving circuit design along with the expansion of the scale of the functional waveguide devices or systems. The third solution is to add an active polarization control device before the functional waveguide device or system to convert the random polarization state coupled from the fiber into a single polarization state. The method comprises the steps of first orthogonally decomposing random polarization into two paths through a polarization separation rotator, rotating the two paths into the same polarization, then realizing high-efficiency beam combination of the two paths of light through phase and intensity modulation, and finally entering a functional waveguide device or system. In the process, the intensity and the phase of the orthogonal component of random polarization have randomness, and the optimal modulation state is found by means of a feedback algorithm. Therefore, the active polarization control scheme increases the power consumption of the system and is complex to operate. In summary, how to realize an on-chip polarization insensitive functional device or system with simple design and compact size becomes a problem to be solved. Disclosure of Invention The present invention provides a method of converting orthogonal polarization states in a waveguide to different modes of a single polarization state to achieve a polarization insensitive functional waveguide device or system. The passive conversion