Author Affiliations
Abstract
Wuhan National Laboratory for Optoelectronics & School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
We propose a design of single-mode orbital angular momentum (OAM) beam laser with high direct-modulation bandwidth. It is a microcylinder/microring cavity interacted with two types of second-order gratings: the complex top grating containing the real part and the imaginary part modulations and the side grating. The side grating etched on the periphery of the microcylinder/microring cavity can select a whispering gallery mode with a specific azimuthal mode number, while the complex top grating can scatter the lasing mode with travelling-wave pattern vertically. With the cooperation of the gratings, the laser works with a single mode and emits radially polarized OAM beams. With an asymmetrical pad metal on the top of the cavity, the OAM on-chip laser can firstly be directly modulated with electrical pumping. Due to the small active volume, the laser with low threshold current is predicted to have a high direct modulation bandwidth about 29 GHz with the bias current of ten times the threshold from the simulation. The semiconductor OAM laser can be rather easily realized at different wavelengths such as the O band, C band, and L band.
orbital angular momentum diffraction and gratings vertical emitting lasers microcavity devices semiconductor lasers single mode directly modulated laser Chinese Optics Letters
2021, 19(8): 081401
Author Affiliations
Abstract
1 CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
2 CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
We have demonstrated a mode matching method between two different fibers by a hybrid thermal expanded core technique, which can be applied to match the modes of fiber-based Fabry–Pérot cavities. Experimentally, this method has achieved an expansion of the ultraviolet fiber core by 3.5 times while keeping fundamental mode propagation. With the experiment parameters, the fundamental mode coupling efficiency between the fiber and micro-cavity can reach 95% for a plano-concave cavity with a length of 400 μm. This method can not only have potential in quantum photonics research but also can be applied in classical optical fields.
060.2310 Fiber optics 120.2230 Fabry-Perot 140.3948 Microcavity devices 020.5580 Quantum electrodynamics Chinese Optics Letters
2019, 17(9): 090601
Author Affiliations
Abstract
1 Image Processing Systems Institute—Branch of the Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, 151 Molodogvardeyskaya St., Samara 443001, Russia
2 Samara National Research University, 34 Moskovskoe Shosse, Samara 443086, Russia
We propose a simple integrated narrowband filter consisting of two grooves on the surface of a slab waveguide. Spectral filtering is performed in transmission at oblique incidence due to excitation of an eigenmode of the structure localized at a ridge cavity between the grooves. For the considered parameters, zero reflectance and unity transmittance are achieved at resonant conditions. The width and location of the transmittance peak can be controlled by changing the widths of the grooves and of the ridge, respectively. The proposed filter may find application in waveguide-integrated spectrometers.
Wavelength filtering devices Microcavity devices Integrated optics devices Guided waves Resonance domain Subwavelength structures Photonics Research
2018, 6(1): 01000061
Author Affiliations
Abstract
State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors & Institute of Material Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100083, China
Relative intensity noise (RIN) and high-speed modulation characteristics are investigated for an AlGaInAs/InP hybrid square-rectangular laser (HSRL) with square side length, rectangular length, and width of 15,300, and 2 μm, respectively. Single-mode operation with side-mode suppression larger than 40 dB has been realized for the HSRL over wide variation of the injection currents. In addition, the HSRL exhibits a 3 dB modulation bandwidth of 15.5 GHz, and an RIN nearly approaches standard quantum shot-noise limit 2hv/P= 164 dB/Hz at high bias currents due to the strong mode selection of the square microcavity. With the increase of the DC bias current of the Fabry–Perot section, significantly enhanced modulation bandwidth and decreased RIN are observed. Furthermore, intrinsic parameters such as resonance frequency, damping factor, and modified Schawlow–Townes linewidth are extracted from the noise spectra.
Microcavity devices Semiconductor lasers Fluctuations, relaxations, and noise Photonics Research
2018, 6(3): 03000193
Author Affiliations
Abstract
1 Laboratory for Optical Systems, Department of Microsystems Engineering, University of Freiburg, Georges-K?hler-Allee 102, 79110 Freiburg, Germany
2 Fraunhofer Institute for Physical Measurement Techniques IPM, Heidenhofstra?e 8, 79110 Freiburg, Germany
A low-cost light-emitting diode (LED) is sufficient to pump a quasi-continuous-wave bidirectional high-Q whispering-gallery resonator laser made of Nd:YVO4. This is remarkable because of the very limited spatial and spectral coherence of an LED. The LED, delivering up to 3.5 W, centered around 810 nm, is turned on in intervals of 100 μs duration, and for these periods a laser output exceeding 0.8 mW has been verified. Furthermore, 0.1-s-long laser pulses are demonstrated. To the best of our knowledge, this is the first demonstration of an LED-pumped high-Q whispering-gallery laser. The concept can be extended easily to other laser active materials. A prospect is also to pump several of such lasers with a single LED.
(140.3530) Lasers neodymium (140.3580) Lasers solid-state (140.3948) Microcavity devices (230.3670) Light-emitting diodes. Photonics Research
2017, 5(6): 06000B34
Author Affiliations
Abstract
State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100083, China
Stable dual-mode semiconductor lasers can be applied for the photonic generation of microwave and terahertz waves. In this paper, the mode characteristics of a variable curvature microresonator are investigated by a two-dimensional finite element method for realizing stable dual-mode lasing. The microresonator features a smooth boundary and the same symmetry as a square resonator. A small variable-curvature microresonator with a radius of 4 μm can support the fundamental four-bounce mode and the circular-like mode simultaneously, with quality factors up to the order of 104 and 105, respectively. The dual modes in the phase space of the Poincaré surface of sections distribute far from each other and can maintain enough stability for dual-mode lasing. Furthermore, the refractive index and waveguide can modulate the dual-mode wavelength difference and quality factors efficiently thanks to the spatially separated fields of these two modes.
(140.3948) Microcavity devices (140.5960) Semiconductor lasers. Photonics Research
2017, 5(6): 06000695
Author Affiliations
Abstract
Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, College of Physics and Energy, Fujian Normal University, Fuzhou 350007, China
It is demonstrated that high-Q (Q～108) bottle microresonators can be fabricated by using a CO2 laser to heat a vertical single-mode fiber with a small weight attached to its lower end. A tunable continuous-wave laser is used to excite whispering-gallery modes in a bottle microresonator through a fiber taper, and a ringing phenomenon is observed. The observed ringing phenomenon is well explained through the numerical solution of a dynamic equation. In addition, an explicit function is given to describe the light field in the resonator, and the theoretical transmission based on the function also agrees very well with the experimental ringing phenomenon.
140.4780 Optical resonators 140.3948 Microcavity devices Chinese Optics Letters
2016, 14(2): 021402
Author Affiliations
Abstract
The State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Hybrid octagonal-ring microlasers are investigated for realizing a stable output from a silicon waveguide based on a two-dimensional simulation. The inner radius of the ring is optimized to achieve single-mode and low-threshold operation. Using the divinylsiloxane-benzocyclobutene (DVS-BCB) bonding technique, a hybrid AlGaInAs/Si octagonal-ring microlaser vertically coupled to a silicon waveguide is fabricated with a side length of 21.6 μm and an inner radius of 15 μm. A single transverse-mode operation is achieved with a threshold current density of 0.8 kA/cm2 and a side-mode suppression ratio above 30 dB, and a stable output from the lower silicon waveguide is obtained.
140.3948 Microcavity devices 250.5960 Semiconductor lasers 250.5300 Photonic integrated circuits Chinese Optics Letters
2016, 14(3): 031402
1 School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
2 Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Integrated photonics requires high gain optical materials in the telecom wavelength range for optical amplifiers and coherent light sources. Erbium (Er) containing materials are ideal candidates due to the 1.5 μm emission from Er3+ ions. However, the Er density in typical Er-doped materials is less than 1020 cm–3, thus limiting the maximum optical gain to a few dB/cm, too small to be useful for integrated photonic applications. Er compounds could potentially solve this problem since they contain much higher Er3+ density. So far the existing Er compounds suffer from short lifetime and strong upconversion effects, mainly due to poor crystal qualities. Recently, we explore a new Er compound: erbium chloride silicate (ECS, Er3(SiO4)2Cl) in the form of nanowire, which facilitates the growth of high quality single crystal with relatively large Er3+ density (1.62 × 1022 cm–3). Previous optical results show that the high crystal quality of ECS material leads to a long lifetime up to 1 ms. The Er lifetime-density product was found to be the largest among all the Er containing materials. Pump-probe experiments demonstrated a 644 dB/cm signal enhancement and 30 dB/cm net gain per unit length from a single ECS wire. As a result, such high-gain ECS nanowires can be potentially fabricated into ultra-compact lasers. Even though a single ECS nanowire naturally serves as good waveguide, additional feedback mechanism is needed to form an ultra-compact laser. In this work, we demonstrate the direct fabrication of 1D photonic crystal (PhC) air hole array structure on a single ECS nanowire using focused ion beam (FIB). Transmission measurement shows polarization-dependent stop-band behavior. For transverse electric (TE) polarization, we observed stop-band suppression as much as 12 dB with a 9 μm long airholed structure. Through numerical simulation, we showed that Q-factor as high as 11000 can be achieved at 1.53 μm for a 1D PhC micro-cavity on an ECS nanowire. Such a high Q cavity combined with the high material gain of ECS nanowires provides an attractive solution for ultra-compact lasers, an important goal of this research.
nanomaterials nanomaterials rare-earth-doped materials rare-earth-doped materials lasers lasers optical amplifiers optical amplifiers nanostructure fabrication nanostructure fabrication microcavity devices microcavity devices Frontiers of Optoelectronics
2016, 9(2): 312
Author Affiliations
Abstract
1 National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences,Nanjing University, Nanjing 210093, China
2 Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
We experimentally demonstrate high optical quality factor silica microdisk resonators on a silicon chip with large wedge angles by reactive ion etching. For 2-μm-thick microresonators, we have achieved wedge angles of 59°, 63°, 70°, and 79° with optical quality factors of 2.4 × 107, 8.1 × 106, 5.9 × 106, and 7.4 × 106, respectively, from ～80 μmdiameter microresonators in the 1550 nm wavelength band. Also, for 1-μm-thick microresonators, we have obtained an optical quality factor of 7.3 × 106 with a wedge angle of 74°.
Optical resonators Optical resonators Microcavity devices Microcavity devices Photonics Research
2015, 3(5): 05000279
