Adjustable on-chip integrated polarizer based on ridge-shaped optical waveguide

Abstract

The invention discloses an adjustable on-chip integrated polarizer based on a ridge-shaped optical waveguide. The adjustable on-chip integrated polarizer comprises a substrate (7), a TE type on-chip integrated polarizer arranged on the substrate (7), and an adjustable layer (4) covering the polarizer, the TE type on-chip integrated polarizer is composed of a ridge-shaped optical waveguide (3), and incident light is input through an input end Input port (5), transmitted along the ridge-shaped optical waveguide (3) in a TE0 polarization mode and a TM0 polarization mode and output through an output end Output port (6). The substrate (7) comprises a crystal single crystal thin film layer (1) and a substrate material layer (2); the TE type on-chip integrated polarizer is prepared on the crystal single crystal thin film layer (1). Compared with the prior art, the on-chip integrated polarizer has the advantages of wide spectral range, ultrahigh extinction ratio and adjustability.

Description

Technical Field

[0001] The invention relates to the fields of transparent integrated photonic chips and quantum communications, and in particular to the design of a polarization division multiplexer with wide working bandwidth and high extinction ratio. Background Art

[0002] Compared with integrated circuits, photonic integrated chips have been widely used in cutting-edge fields of science and technology such as optical communication, quantum information and optical storage due to their advantages such as wide bandwidth, low loss and low latency. However, polarization-related issues such as polarization crosstalk and polarization dispersion of optical signals have always been one of the main obstacles restricting the further development of photonic integrated chips. For example, the power value change caused by the optical signal passing through passive devices in the case of polarization will be amplified in the transmission of optical fiber links, causing huge losses, namely polarization-related losses; polarization-related wavelength shift will affect the central wavelength and channel spacing of the channel in the wavelength division multiplexing device; polarization mode dispersion will have a negative impact on the data transmission distance and efficiency in photonic integrated chips. In addition, in the field of nonlinear optics, the phase matching of polarization modes will also affect the working performance of nonlinear photonic integrated devices. Therefore, on-chip integrated optical components with polarization control functions, such as polarizers, polarization rotators (PRs) and polarization beam splitters (PBSs), play an important role in regulating the polarization state in photonic integrated chips.

[0003] On-chip integrated polarizers are widely used in photonic integrated chips as polarization filters to minimize polarization crosstalk. In order to realize wide-bandwidth on-chip integrated polarizers with high polarization extinction ratio (PER), various experimental schemes have been studied and proposed. The most commonly used method is to absorb, reflect or leak unwanted polarization modes by designing specific waveguide structures with strong polarization-dependent losses, thereby achieving single polarization mode output. The size of the on-chip integrated polarizer using shallowly etched ridge optical waveguides proposed earlier was about 1 mm, which was not suitable for high-density integrated photonic chips. Therefore, compact silicon-based polarizers with hybrid plasma structures were proposed to reduce the device footprint, but the insertion losses (ILs) were increased due to the light absorption of metals. Although low-loss polarizers can be achieved using two-dimensional materials. However, graphene-based material structures are incompatible with large-scale COMS processes. In order to achieve polarizers with high polarization extinction ratio, low loss and wide working bandwidth, researchers have proposed subwavelength gratings (SWGs), shallowly etched optical waveguide structures and slot waveguide structures, which require complex processing techniques. On-chip integrated polarizers based on grating structures can achieve high polarization extinction ratio and wide operating bandwidth, but the waveguide structure has a certain back reflection effect and will also cause light loss.

[0004] On-chip integrated polarizers usually transmit a fixed polarization mode in a specific waveguide structure, and it is difficult to modulate the transmitted polarization mode in real time. However, adjustable polarization integrated polarizers play an important role in polarization-sensitive photonic integrated chips, and can adjust the transmitted polarization mode in real time according to the functional requirements of the integrated photonic devices. Polarization control of the polarizer can be achieved by external mechanical rotation of the polarization regulator or by utilizing the optical fiber compression birefringence effect, but these methods are not applicable to polarization control of integrated devices. At present, studies have reported the use of thermo-optical effect, carrier dispersion effect and electro-optical effect to achieve polarization modulation of on-chip integrated polarizers, but the design and preparation of these devices are very difficult, and the polarization control performance is unstable. Summary of the invention

[0005] In view of the technical problems existing in the above-mentioned prior art, the present invention aims to propose an adjustable on-chip integrated polarizer based on a ridge optical waveguide, in which a layer of temperature-controlled phase change material film is covered on the ridge optical waveguide. Under heating conditions, the refractive index of the material film decreases, and the effective refractive index of the TM0 polarization mode transmitted in the ridge optical waveguide is restored to the refractive index value when there is no covering material film. The transmission loss of the TM0 polarization mode in the ridge optical waveguide is relatively large, and only the TE0 polarization mode can be transmitted with low loss in the ridge optical waveguide. The ridge optical waveguide plays a polarizing role, thereby realizing an adjustable on-chip integrated polarizer.

[0006] The present invention is achieved by the following technical solutions:

[0007] An adjustable on-chip integrated polarizer based on a ridge optical waveguide comprises a substrate 7 and a TE-type on-chip integrated polarizer arranged on the substrate 7, wherein the TE-type on-chip integrated polarizer is composed of a ridge optical waveguide 3, and an adjustable layer 4 is covered on the TE-type on-chip integrated polarizer; incident light is input from an input port 5, is transmitted along the linear ridge optical waveguide 3 in a TE0 polarization mode and a TM0 polarization mode, and is output through an output port 6; the substrate 7 comprises a crystal single crystal thin film layer 1 and a substrate material layer 2.

[0008] In some embodiments, the adjustable layer 4 is made of a temperature-controlled phase-change material film, and the polarizing function of the TE-type on-chip integrated polarizer is modulated by heating and adjusting the refractive index of the temperature-controlled phase-change material film.

[0009] In some embodiments, the ridge width W and the outer ridge height h of the ridge-shaped optical waveguide 3 meet single-mode light transmission conditions.

[0010] In some embodiments, the light field energy of the TE0 polarization mode is distributed along a direction parallel to the plane of the ridge optical waveguide 3; and the light field energy of the TM0 polarization mode is distributed along a direction perpendicular to the plane of the ridge optical waveguide 3.

[0011] In some embodiments, by adjusting the outer ridge height h and ridge width W of the ridge optical waveguide 3 , the ridge width W of the ridge optical waveguide is increased, and the outer ridge height h of the ridge optical waveguide 3 is reduced, so that only the TE0 polarization mode is transmitted along the ridge optical waveguide 3 .

[0012] In some embodiments, the effective refractive indexes of the TE0 and TM0 polarization modes in the ridge optical waveguide 3 are different, the effective refractive index of the TE0 polarization mode is large, and the effective refractive index of the TM0 polarization mode is small enough to be close to the effective refractive index of the substrate material layer 2 .

[0013] In some embodiments, the transmission loss of the TM0 polarization mode in the ridge optical waveguide 3 is greater than the optical transmission loss of the TE0 polarization mode.

[0014] In some embodiments, the operating wavelength range of the TE-type on-chip integrated polarizer covers a wide wavelength range from visible light to near-infrared light, and has a high polarization extinction ratio.

[0015] In some implementations, the ridge optical waveguide 3 is a straight ridge optical waveguide or a curved ridge optical waveguide.

[0016] Compared with the prior art, the advantages and positive technical effects achieved by the present invention are as follows:

[0017] 1) A layer of temperature-controlled phase-change material film is covered on the ridge optical waveguide. Under room temperature conditions, the refractive index of the material film is large, and the effective refractive index of the TM0 polarization mode transmitted in the ridge optical waveguide is increased compared with when there is no covering material film. At this time, both the TE0 polarization mode and the TM0 polarization mode can be transmitted in the ridge optical waveguide with low loss, and the polarization effect of the ridge optical waveguide is eliminated; A layer of temperature-controlled phase-change material film is covered on the ridge optical waveguide. Under heating conditions, the refractive index of the material film decreases, and the effective refractive index of the TM0 polarization mode transmitted in the ridge optical waveguide is restored to the refractive index value when there is no covering material film. The transmission loss of the TM0 polarization mode in the ridge optical waveguide is large, and only the TE0 polarization mode can be transmitted in the ridge optical waveguide with low loss. The ridge optical waveguide plays a polarization role, thereby realizing a wide spectral range, ultra-high extinction ratio and adjustable on-chip integrated polarizer;

[0018] 2) It provides feasibility for polarization control of integrated photonic devices and their applications in quantum communication and other fields;

[0019] 3) Using a simple ridge optical waveguide structure, an on-chip integrated polarizer with high extinction ratio is realized in a wide spectral range from visible light to near infrared. The processing tolerance of the polarizer is large and it can be applied to a variety of crystal materials such as silicon nitride;

[0020] 4) The on-chip integrated polarization device has a simple structure and stable performance, which provides more feasibility and flexibility for polarization control of photonic integrated chips and has important application value in cutting-edge scientific and technological fields such as optical communications and quantum information;

[0021] 5) The transmission losses of the TE0 and TM0 polarization modes in the ridge optical waveguide are very small, less than 1 dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an on-chip integrated polarizer based on a ridge optical waveguide of the present invention, wherein (a) is the structure of the on-chip integrated polarizer based on a ridge optical waveguide under room temperature conditions, and (b) is the equivalent structure of the on-chip integrated polarizer based on a ridge optical waveguide under high temperature conditions, which only has a substrate and a linear ridge optical waveguide;

[0023] Figure 2 Figure 3 is a curve of the change of effective refractive index with waveguide height and a light field distribution diagram, where (a) is a curve of the change of effective refractive index of TE0 / TM0 polarization mode in a ridge waveguide; b) is a curve of the change of effective refractive index of TE0 / TM0 polarization mode in a ridge waveguide after covering the adjustable layer, (c) is the light field distribution of TE0 polarization mode in a ridge waveguide at a wavelength of 1550nm; (d) is the light field distribution of TM0 polarization mode in a ridge waveguide at a wavelength of 1550nm, (e) is the light field distribution of TE0 polarization mode in a ridge waveguide after covering the adjustable layer, (f) is the light field distribution of TM0 polarization mode in a ridge waveguide after covering the adjustable layer;

[0024] Figure 3 Figures 1 and 2 are light propagation mode diagrams of TE0 polarization mode and TM0 polarization mode in a linear ridge waveguide, respectively, where (a) is the light propagation mode of TE0 polarization mode in a linear ridge waveguide at a wavelength of 1500nm, (b) is the light propagation mode of TE0 polarization mode in a linear ridge waveguide at a wavelength of 1600nm, (c) is the light propagation mode of TE0 polarization mode in a linear ridge waveguide at a wavelength of 1700nm; (d) is the light propagation mode of TM0 polarization mode in a linear ridge waveguide at a wavelength of 1500nm, (e) is the light propagation mode of TM0 polarization mode in a linear ridge waveguide at a wavelength of 1600nm, (f) is the light propagation mode of TM0 polarization mode in a linear ridge waveguide at a wavelength of 1700nm;

[0025] Figure 4: are transmission spectra in the ridge optical waveguide within the wavelength range of 1500-1700 nm, wherein (a) is the transmission spectrum of the TE0 polarization mode in the ridge optical waveguide, (b) is the transmission spectrum of the TM0 polarization mode in the ridge optical waveguide, (c) is the transmission spectrum of the TE0 polarization mode in the ridge optical waveguide after covering the adjustable layer, and (d) is the transmission spectrum of the TM0 polarization mode in the ridge optical waveguide after covering the adjustable layer;

[0026] Figure 5 The figures are transmission spectra of on-chip integrated polarizers with different outer ridge heights and ridge widths, wherein (a) is the transmission spectrum of TE0 polarization mode, and (b) is the transmission spectrum of TM0 polarization mode; (c) is the transmission spectrum of TE0 polarization mode in the on-chip integrated polarizers with different outer ridge heights and ridge widths after being covered with a high refractive index material film, and (d) is the transmission spectrum of TM0 polarization mode in the on-chip integrated polarizers with different outer ridge heights and ridge widths after being covered with a high refractive index material film;.

[0027] Figure 6 The transmission spectrum test diagram of the integrated polarizer on the silicon nitride wafer, wherein (a) is the transmission spectrum test diagram of the integrated polarizer on the silicon nitride wafer in the TE0 and TM0 polarization modes, and (b) is the transmission spectrum test diagram of the integrated polarizer on the silicon nitride wafer in the TE0 and TM0 polarization modes after covering with a high refractive index material film;

[0028] Reference numerals:

[0029] 1. Crystal single crystal thin film layer, 2. Substrate material layer, 3. Ridge optical waveguide, 4. Adjustable layer, 5. Input port, 6. Output port, 7. Substrate, 8. Air layer, 9. Si3N4 crystal single crystal thin film layer, 10. SiO2 substrate material layer. DETAILED DESCRIPTION

[0030] The technical solution will be clearly described below in conjunction with the accompanying drawings and embodiments.

[0031] Embodiment 1:

[0032] like Figure 1As shown in (a), an adjustable on-chip integrated polarizer based on a ridge optical waveguide of the present invention has a specific structure including a substrate 7 and a TE type on-chip integrated polarizer arranged on the substrate 7. The substrate 7 is composed of a substrate material layer 2 and a crystal single crystal thin film layer 1 arranged on the substrate material layer 2. The crystal single crystal thin film layer 1 is made of a silicon nitride (Si3N4) material film, and the substrate material layer 2 is made of a silicon dioxide SiO2 material. The TE type on-chip integrated polarizer is prepared on a silicon nitride single crystal film; the TE type on-chip integrated polarizer is composed of a ridge optical waveguide 3, in which the incident light is input from the input port 5; in the TE type on-chip integrated polarizer, the incident light is transmitted along the linear ridge optical waveguide 3 in the TE0 polarization mode and the TM0 polarization mode, and output through the output port 6; only the TE0 polarization mode can be transmitted along the ridge optical waveguide 3 and output through the optical signal output port 6; the TE type on-chip integrated polarizer is covered with an adjustable layer 4, and the adjustable layer 4 adopts a temperature-controlled phase change material. When covered on the ridge optical waveguide under room temperature conditions, there is no polarization effect; when covered on the ridge optical waveguide under high temperature conditions, polarization is achieved, thereby realizing an adjustable integrated polarizer, that is, the function of the adjustable on-chip integrated polarizer can be modulated by the refractive index change of the covered temperature-controlled phase change material film; the TE type on-chip integrated polarizer is used to eliminate the polarization effect, and can transmit TE0 and TM0 polarization modes with low loss.

[0033] Furthermore, the ridge optical waveguide used in the present invention can be a straight line or a curved line. The polarizer based on the curved ridge optical waveguide has a smaller size and a higher extinction ratio.

[0034] Furthermore, the adjustable on-chip integrated polarizer based on the ridge optical waveguide of the present invention can be applied to various crystal materials such as silicon nitride.

[0035] Furthermore, the adjustable layer 4 is made of a temperature-controlled phase-change material film, and the polarizing function of the TE-type on-chip integrated polarizer is modulated by heating and adjusting the refractive index of the temperature-controlled phase-change material film.

[0036] Furthermore, the ridge width W and outer ridge height h of the ridge-shaped optical waveguide meet single-mode optical transmission conditions.

[0037] Furthermore, the light field energy in the TE0 polarization mode is distributed along a direction parallel to the plane of the ridge optical waveguide; and the light field energy in the TM0 polarization mode is distributed along a direction perpendicular to the plane of the ridge optical waveguide.

[0038] Furthermore, by adjusting the outer ridge height h and ridge width W of the ridge optical waveguide, the ridge width W of the ridge optical waveguide is increased, and the outer ridge height h of the ridge optical waveguide is reduced, so that only the TE0 polarization mode is transmitted along the ridge optical waveguide, and the TM0 polarization mode cannot be transmitted along the ridge optical waveguide.

[0039] Furthermore, the effective refractive indexes of the TE0 and TM0 polarization modes in the ridge optical waveguide are different, the effective refractive index of the TE0 polarization mode is large, and the effective refractive index of the TM0 polarization mode is small enough to be close to the effective refractive index of the substrate material.

[0040] Furthermore, the transmission loss of the TM0 polarization mode in the ridge optical waveguide is greater than the optical transmission loss of the TE0 polarization mode.

[0041] Furthermore, the operating wavelength range of the TE-type on-chip integrated polarizer covers a wide wavelength range from visible light to near-infrared light, and has a high polarization extinction ratio.

[0042] Furthermore, the ridge optical waveguide 3 is a straight ridge optical waveguide or a curved ridge optical waveguide.

[0043] The on-chip integrated polarizer is a simple linear ridge optical waveguide structure based on single-mode light transmission, which is prepared on a silicon nitride film. The working principle of the on-chip integrated polarizer is that the TE0 polarization mode can pass through the linear ridge optical waveguide with low loss, while the TM0 polarization mode will leak into the SiO2 substrate material. However, after the linear ridge optical waveguide is covered with an adjustable layer, both the TE0 and TM0 polarization modes can be transmitted in the ridge optical waveguide with low loss, and the polarization effect is eliminated, such as Figure 2 As shown in (a) and (b).

[0044] Due to the asymmetry of the cross section of the ridge waveguide structure, the effective refractive indexes of the transmitted TE0 and TM0 polarization modes are different. Increasing the ridge width W of the ridge waveguide and reducing the outer ridge height h of the ridge waveguide can make the effective refractive index of the TE0 polarization mode greater than that of the TM0 mode. When the ridge width W of the ridge waveguide is 800nm, the effective refractive indexes of the TE0 and TM0 polarization modes decrease as the outer ridge height h of the ridge waveguide decreases, as shown in FIG. Figure 2(a). When the outer ridge height h is lower than 380nm, the effective refractive index of the TM0 polarization mode is close to the refractive index of the substrate material SiO2, which means that due to the poor constraint of the ridge optical waveguide on the TM0 polarization mode, the TM0 polarization mode will leak into the SiO2 substrate. Therefore, when the ridge width W of the linear ridge optical waveguide is 800nm ​​and the outer ridge height h is 100nm, only the TE0 polarization mode is transmitted with low loss, while the TM0 polarization mode will produce a large transmission loss, thereby realizing the role of a polarizer. At an operating wavelength of 1550nm, the effective refractive indices of the TE0 and TM0 polarization modes transmitted in the linear ridge optical waveguide are approximately 1.534 and 1.44, respectively, ensuring the good working performance of the on-chip polarizer. The optical field distribution of the TE0 and TM0 polarization modes in the linear ridge optical waveguide is shown in the figure. Figure 2 As shown in (c) and (d).

[0045] Covering the ridge optical waveguide with an adjustable layer 4 can increase the effective refractive index of the TE0 and TM0 polarization modes. The curve of the refractive index changing with the outer ridge height h of the linear ridge optical waveguide is shown in FIG. Figure 2 (b). Although the effective refractive index of the TE0 and TM0 polarization modes decreases with the decrease of the outer ridge height h, when the outer ridge height h is 100nm, the effective refractive index of the TM0 polarization mode is about 1.53, which is greater than the effective refractive index of the SiO2 substrate material. This is because covering the linear ridge optical waveguide with a layer of high refractive index material film can enhance the ability to constrain the light field energy of the TM0 polarization mode distributed perpendicular to the surface direction of the ridge optical waveguide. Therefore, after covering with a layer of material film (8), the TE0 and TM0 polarization modes can be well confined in the waveguide. Figure 2 As shown in (e) and 2(f), after the adjustable layer 4 is covered on the linear ridge optical waveguide, both the TE0 and TM0 polarization modes can be transmitted with low loss in the ridge optical waveguide, and the polarization effect is eliminated.

[0046] Figure 3 (a)-3(f) show the light transmission of the TE0 and TM0 polarization modes in the linear ridge optical waveguide at 1500, 1600 and 1700 nm wavelengths, respectively. It shows that the TE0 polarization mode passes through the linear ridge optical waveguide with low loss in the wavelength range of 1500-1700 nm, while the light transmission loss of the TM0 polarization mode in the linear ridge optical waveguide is large, and the light loss increases with the increase of wavelength.

[0047] According to simulation calculation results, within the wavelength range of 1540-1700nm, the polarization extinction ratio of the TM0 polarization mode exceeds 40db, with the highest value reaching 60dB, and the transmission loss of the TE0 polarization mode is less than 1dB. Figure 4 (a and (b). After the ridge optical waveguide is covered with an adjustable layer, the transmission losses of the TE0 and TM0 polarization modes are both less than 0.6 dB in the wavelength range of 1500 nm to 1700 nm, and the transmission loss of the TE0 polarization mode is less than that of the TM0 polarization mode, as shown in FIG. Figure 4 As shown in (c) and (d).

[0048] The on-chip integrated polarizer has a larger processing tolerance. Figure 5 (a) and (b) show the transmission spectra of the TE0 and TM0 polarization modes in the on-chip integrated polarizer when the ridge width W and the outer ridge height h of the ridge optical waveguide vary by ±10 nm. The TE-type on-chip integrated polarizers with different waveguide sizes all maintain low insertion loss and high polarization extinction ratio, confirming that the on-chip integrated polarizer has a large processing tolerance. Figure 5 As shown in (c) and (d), after the linear ridge optical waveguides of different waveguide sizes are covered with a high refractive index material film 4, both the TE0 and TM0 polarization modes can be transmitted with low loss in the linear ridge optical waveguides of different ridge widths W and outer ridge heights h, and the transmission loss is less than 1 dB. Therefore, the on-chip integrated polarizer based on a simple linear ridge optical waveguide structure has a good processing tolerance.

[0049] The transmission spectrum of the fabricated on-chip integrated polarizer based on a silicon nitride linear ridge optical waveguide structure was experimentally measured. Figure 6 As shown in (a). The TM0 polarization mode achieves an operating bandwidth of 100nm in the on-chip integrated polarizer, and the polarization extinction ratio is greater than 25dB. The polarization extinction ratio is greater than 40dB in the wavelength range of 1560-1640nm, and the polarization extinction ratio peak is 53dB at 1595nm. Limited by the operating wavelength range of the test laser (1510-1640nm), the actual operating wavelength of the on-chip integrated polarizer can be extended to 1700nm. Therefore, the operating bandwidth of the on-chip integrated polarizer should be greater than 100nm. The measured value of the optical transmission loss of the TE0 polarization mode in the on-chip integrated polarizer is less than 1dB. The transmission spectrum of the on-chip integrated polarizer covered with a layer of high refractive index material film was experimentally measured, as shown in Figure 6(b). The transmission loss of the TM0 polarization mode in the on-chip integrated polarizer is significantly reduced, and the transmission losses of the TE0 and TM0 polarization modes in the on-chip integrated polarizer are both less than 1 dB. Therefore, after covering the adjustable layer 4, the polarization effect of the on-chip integrated polarizer is eliminated, and the TE0 and TM0 polarization modes are transmitted as a common ridge optical waveguide with low loss.

[0050] Experimental test results: Therefore, the adjustable on-chip integrated polarizer based on the ridge optical waveguide of the present invention can realize single polarization state transmission with high polarization extinction ratio in a wide operating wavelength range.

[0051] Embodiment 2:

[0052] The present invention discloses a method for preparing an adjustable on-chip integrated polarizer based on a ridge optical waveguide, which uses micro-nano processing techniques such as electron beam exposure technology and inductively coupled plasma etching technology to prepare a ridge optical waveguide structure on a single crystal thin film heterostructure, such as a silicon nitride thin film, according to the designed structural size and morphology. For example, for a silicon nitride thin film heterostructure with a thickness of 360 nanometers, the preparation of an on-chip integrated polarizer based on a silicon nitride ridge optical waveguide can be achieved according to the following method steps:

[0053] Specific embodiment: a layer of temperature-controlled phase-change material film is covered on the prepared ridge optical waveguide to realize an adjustable on-chip integrated polarizer; incident light is input from the input port of the on-chip integrated polarizer, transmitted in the ridge optical waveguide, and finally outputs TE polarization mode light at the output port; the outer ridge height h and ridge width W of the ridge optical waveguide are adjusted to realize the transmission of the TE0 polarization mode with high extinction ratio along the ridge optical waveguide, while suppressing the transmission of the TM0 polarization mode along the ridge optical waveguide. The TE-type on-chip integrated polarizer is based on a ridge optical waveguide, which can be a straight ridge optical waveguide or a curved ridge optical waveguide. The polarizer based on the curved ridge optical waveguide has a smaller size and a higher extinction ratio. A layer of temperature-controlled phase-change material film is covered on the ridge optical waveguide. Under room temperature conditions, the refractive index of the phase-change material film is relatively large, which can effectively limit the low-loss transmission of the TE0 and TM0 polarization modes in the ridge optical waveguide. At this time, the polarization effect of the ridge optical waveguide is eliminated; under high temperature conditions, the refractive index of the phase-change material film decreases, and the transmission loss of the TM0 polarization mode in the ridge optical waveguide is relatively large. Only the TE0 polarization mode can be transmitted in the ridge optical waveguide with low loss, while the TM0 polarization mode cannot be transmitted in the ridge optical waveguide. At this time, the ridge optical waveguide realizes an integrated polarizer. Therefore, an adjustable on-chip integrated polarizer is realized. The adjustable on-chip integrated polarizer based on the ridge optical waveguide of the present invention can be applied to a variety of crystal materials. Compared with the prior art, the present invention realizes an adjustable on-chip integrated polarizer with ultra-high extinction ratio in a wide spectral range from visible light to near-infrared bands, which provides feasibility for the application of polarization control in transparent integrated photonic chips and quantum communications.

[0054] Based on the embodiments of the present invention, all other embodiments and technical replacements and modifications of the embodiments obtained by ordinary technicians in the field without departing from the spirit of the present invention and without making creative work shall fall within the scope of protection of the present invention.

Claims

1. An adjustable on-chip integrated polarizer based on a ridge optical waveguide, characterized in that: The invention comprises a substrate (7) and a TE-type on-chip integrated polarizer arranged on the substrate (7), wherein the TE-type on-chip integrated polarizer is composed of a ridge-shaped optical waveguide (3), and an adjustable layer (4) is covered on the TE-type on-chip integrated polarizer; incident light is input through an input port (5), transmitted along the ridge-shaped optical waveguide (3) in a TE0 polarization mode and a TM0 polarization mode, and output through an output port (6); the substrate (7) comprises a crystal single crystal thin film layer (1) and a substrate material layer (2).

2. The adjustable on-chip integrated polarizer based on a ridge optical waveguide according to claim 1, characterized in that: The adjustable layer (4) is made of a temperature-controlled phase-change material film, and the polarizing function of the TE-type on-chip integrated polarizer is modulated by heating and adjusting the refractive index of the temperature-controlled phase-change material film.

3. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The ridge width W and outer ridge height h of the ridge-shaped optical waveguide (3) meet the single-mode light transmission conditions.

4. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The light field energy of the TE0 polarization mode is distributed along a direction parallel to the plane of the ridge-shaped optical waveguide (3); and the light field energy of the TM0 polarization mode is distributed along a direction perpendicular to the plane of the ridge-shaped optical waveguide (3).

5. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: By adjusting the outer ridge height h and the ridge width W of the ridge optical waveguide (3), the ridge width W of the ridge optical waveguide (3) is increased, and the outer ridge height h of the ridge optical waveguide (3) is reduced, so that only the TE0 polarization mode is transmitted along the ridge optical waveguide (3).

6. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The effective refractive indexes of the TE0 and TM0 polarization modes in the ridge optical waveguide (3) are different, the effective refractive index of the TE0 polarization mode is large, and the effective refractive index of the TM0 polarization mode is small enough to be close to the refractive index of the substrate material layer (2).

7. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The transmission loss of the TM0 polarization mode in the ridge optical waveguide (3) is greater than the optical transmission loss of the TE0 polarization mode.

8. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The working wavelength range of the TE-type on-chip integrated polarizer covers a wide wavelength range from visible light to near infrared light.

9. The adjustable on-chip integrated polarizer based on ridge optical waveguide according to claim 1, characterized in that: The ridge-shaped optical waveguide (3) is a straight-type ridge-shaped optical waveguide or a curved-type ridge-shaped optical waveguide.

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