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Chen D, Chen Z, Yang Y, Wang Y, Han X, Lau KY, Wu Z, Zou C, Zhang Y, Xu B, Liu X, Ma Z, Dong G, Barillaro G, Zhong L, Qiu J. 3D Laser Writing of Low-Loss Cross-Section-Variable Type-I Optical Waveguide Passive/Active Integrated Devices in Single Crystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2404493. [PMID: 38718355 DOI: 10.1002/adma.202404493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/01/2024] [Indexed: 06/14/2024]
Abstract
Optical waveguides fabricated in single crystals offer crucial passive/active optical components for photonic integrated circuits. Single crystals possess inherent advantages over their amorphous counterpart, such as lower optical losses in visible-to-mid-infrared band, larger peak emission cross-section, higher doping concentration. However, the writing of Type-I positive refractive index modified waveguides in single crystals using femtosecond laser technology presents significant challenges. Herein, this work introduces a novel femtosecond laser direct writing technique that combines slit-shaping with an immersion oil objective to fabricate low-loss Type-I waveguides in single crystals. This approach allows for precise control of waveguide shape, size, mode-field, and refractive index distribution, with a spatial resolution as high as 700 nm and a high positive refractive index variation on the order of 10-2, introducing new degrees of freedom to design and fabricate passive/active optical waveguide devices. As a proof-of-concept, this work successfully produces a 7 mm-long circular-shaped gain waveguide (≈10 µm in diameter) in an Er3+-doped YAG single crystal, exhibiting a propagation loss as low as 0.23 dB cm-1, a net gain of ≈3 dB and a polarization-insensitive character. The newly-developed technique is theoretically applicable to arbitrary single crystals, holding promising potential for various applications in integrated optics, optical communication, and photonic quantum circuits.
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Affiliation(s)
- Daoyuan Chen
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhi Chen
- Zhejiang Lab, Hangzhou, 311100, China
- College of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, Yunnan, 650093, China
| | - Yi Yang
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Yuying Wang
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Xuhu Han
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Kuen Yao Lau
- Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, School of Optoelectronic Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, China
| | - Zhemin Wu
- School of Material Science and Engineering, Centre of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027, China
| | - Chen Zou
- School of Material Science and Engineering, Centre of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027, China
| | - Yu Zhang
- Zhejiang Lab, Hangzhou, 311100, China
| | - Beibei Xu
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Xiaofeng Liu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhijun Ma
- Zhejiang Lab, Hangzhou, 311100, China
| | - Guoping Dong
- State Key Laboratory of Luminescent Materials and Devices, and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56126, Italy
| | - Lijing Zhong
- Institute of Light+X Science and Technology, College of Information Science and Engineering, Ningbo University, Ningbo, 315211, China
| | - Jianrong Qiu
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China
- Institute of Light+X Science and Technology, College of Information Science and Engineering, Ningbo University, Ningbo, 315211, China
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Tao S, Song H, Zhao D, Yang Y, Wang S, Yan J, Wei J, Wang X, Qin G, Wang F, Zhang D. Strip loaded waveguide amplifiers based on erbium-doped nanocomposites with 17 dB internal net gain. OPTICS EXPRESS 2024; 32:7931-7939. [PMID: 38439462 DOI: 10.1364/oe.514318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 02/05/2024] [Indexed: 03/06/2024]
Abstract
We propose a strip loaded amplifier employing SU-8 as the loaded waveguide and nanoparticles (NPs)-polymethyl methacrylate (PMMA) as the cladding layer. By leveraging the undoped SU-8 loaded waveguide, the polymer waveguide amplifier accomplished remarkably low transmission losses, reaching as low as 1.8 dB/cm at 1530 nm. We prepared NPs-PMMA nanocomposite by utilizing NaLu0.1Y0.7F4: Er3+, Yb3+ @NaLuF4 core-shell nanoparticles, which exhibited a significantly enhanced lifetime of 6.15 ms. An internal net gain of up to 17.7 dB was achieved on a strip loaded waveguide with a length as short as 0.5 cm when the on-chip pump power was 77 mW. Signal enhancement (SE) was measured at different wavelengths, revealing that the strip loaded waveguide exhibited broadband SE ranging from 1510 nm to 1570 nm, covering the C-band. To the best of our knowledge, this work has achieved the highest gain results reported thus far on a polymer matrix and provides an efficient method for optical amplification in passive devices on silicon and Si3N4 platforms, leveraging the ease of integration of polymer materials with diverse photonic platforms.
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Yu C, Wang F, Gao L, Shi J, Li C, Zhao D, Zhang M, Hu G. Improvement of differential modal gain in a ring-core few-mode erbium-doped polymer optical waveguide amplifier. OPTICS EXPRESS 2024; 32:6121-6129. [PMID: 38439322 DOI: 10.1364/oe.514675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/23/2024] [Indexed: 03/06/2024]
Abstract
A few-mode erbium-doped waveguide amplifier (FM-EDWA) with a confined Er3+ doped ring structure is proposed to equalize the differential modal gain (DMG). The FM-EDWA amplifying three spatial modes (LP01, LP11a and LP11b) is optimized by genetic algorithm and fabricated using precise lithography overlay alignment technology. We observe gain values of over 14 dB for all modes with DMG of 0.73 dB at 1529 nm pumped only with LP01 for the power of 200 mW. Furthermore, a flat gain of more than 10 dB is demonstrated across 1525-1565 nm, with a sufficiently low DMG of less than 1.3 dB.
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Sun X, Chen Z, Zhang L, Chen D, Wang Y, Xu B, Ma Z, Barillaro G, Zhong L, Qiu J. Toward a10 dB net-gain waveguide amplifier in an Er 3+-Yb 3+ co-doped phosphate glass. OPTICS LETTERS 2024; 49:33-36. [PMID: 38134145 DOI: 10.1364/ol.511729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023]
Abstract
High-gain materials and high-quality structures are the two main conditions that determine the amplification performance of optical waveguides. However, it has been hard to balance each other, to date. In this work, we demonstrate breakthroughs in both glass optical gain and optical waveguide structures. We propose a secondary melting dehydration technique that prepares high-quality Er3+-Yb3+ co-doped phosphate glass with low absorption loss. Additionally, we propose a femtosecond laser direct-writing technique that allows controlling the cross section, size, and mode field of waveguides written in glass with high accuracy, leveraging submicron-resolution multi-scan direct-writing optical waveguide technology, which is beneficial for reducing insertion loss. As a proof of concept demonstration, we designed and fabricated two kinds of waveguides, namely, LP01- and LP11-mode waveguides in the Er3+-Yb3+ co-doped phosphate glass, enabling insertion loss as low as 0.9 dB for a waveguide length of 2 mm. Remarkably, we successfully achieved an optical amplification for both the waveguides with a net gain of >7 dB and a net-gain coefficient of >3.5 dB/mm, which is approximately one order of magnitude larger than that in the Er3+-Yb3+ co-doped phosphate glass fabricated by the traditional melt-quenching method. This will open new avenues toward the development of integrated photonic chips.
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Tang G, Song X, Huang W, Wu M, Zhang F, Zhao W, Qian Q, Yang Z. Broadband near-infrared amplified spontaneous emission of Er 3+-doped germanate glass fiber. OPTICS LETTERS 2023; 48:5423-5426. [PMID: 37831883 DOI: 10.1364/ol.501342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023]
Abstract
Er3+-doped glass and fiber are very attractive for near-infrared (NIR) lasers and photonic applications. In this work, the full width at half maximum (FWHM) of NIR fluorescence emission of the Er3+-doped germanate glass can be broadened from 72 to 99 nm when Al2O3 was added. In addition, the spectroscopic properties, including absorption and emission spectra, Judd-Ofelt intensity parameters, absorption and emission cross sections, gain coefficient, and fluorescence lifetime, of the Al2O3-modified germanate glass were systematically investigated. What is more, silicate-clad heavily Er3+-doped germanate core multimaterial fibers were successfully drawn by a rod-in-tube method. Notably, broadband NIR amplified spontaneous emission (ASE) with an FWHM of 120 nm was achieved in this new fiber. To the best of our knowledge, this is the largest FWHM reported for Er3+-doped germanate glass fibers. These results suggest that the as-drawn Er3+-doped germanate glass fiber with superior performances is a promising candidate for broadband optical amplification.
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