1
|
Yadav P, Xinhou C, Bhatt S, Das S, Yang H, Mishra R. Highly Efficient Spintronic Terahertz Emitter Utilizing a Large Spin Hall Conductivity of Type-II Dirac Semimetal PtTe 2. NANO LETTERS 2024; 24:2376-2383. [PMID: 38329912 DOI: 10.1021/acs.nanolett.3c04986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The remarkable spin-charge interconversion ability of transition metal dichalcogenides (TMDs) makes them promising candidates for spintronic applications. Nevertheless, their potential as spintronic terahertz (THz) emitters (STEs) remains constrained mainly due to their sizable resistivity and low spin Hall conductivity (SHC), which consequently result in modest THz emission. In this work, the TMD PtTe2, a type-II Dirac semimetal is effectively utilized to develop efficient STEs. This high efficiency primarily results from the large SHC of PtTe2, stemming from its low resistivity and significant spin-to-charge conversion efficiency, attributed to surface states and the local Rashba effect in addition to the inverse spin Hall effect. Remarkably, the peak THz emission from PtTe2/Co-STE exceeds that of Pt/Co-STE by ∼15% and is nearly double that of a similarly thick Pt/Co-STE. The efficient THz emission in the PtTe2/Co heterostructure opens new possibilities for utilizing the semimetal TMDs for developing THz emitters.
Collapse
Affiliation(s)
- Pinki Yadav
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Delhi 110016, India
| | - Chen Xinhou
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576
| | - Shubham Bhatt
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Delhi 110016, India
| | - Samaresh Das
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Delhi 110016, India
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576
| | - Rahul Mishra
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Delhi 110016, India
| |
Collapse
|
2
|
Wu JL, Huang YL, Yang YD, Xiao JL, Qin GS, Huang YZ. Wideband multiwavelength Brillouin fiber laser based on dual-mode AlGaInAs/InP microcavity lasers. APPLIED OPTICS 2020; 59:363-369. [PMID: 32225320 DOI: 10.1364/ao.59.000363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 11/23/2019] [Indexed: 06/10/2023]
Abstract
A multiwavelength Brillouin fiber laser (BFL) is demonstrated using a 1.55-µm AlGaInAs/InP microcavity laser as a seed source. The combination of a nonlinear fiber cavity and a feedback loop leads to multiwavelength generation with a channel spacing of double-Brillouin-frequency assisted by cavity-enhanced four-wave mixing. The amplified output of a dual-mode lasing square microcavity laser with a wavelength interval of 1.5 nm is applied as the pump source for the broadband multiwavelength generation. A wideband multiwavelength BFL covering from 1490 nm to 1590 nm is successfully generated at an optimized pump power of 25 dBm and a feedback power of -17.2dBm. The power stability of 0.82 dB over a 60 min duration of the multiwavelength BFL can satisfy the demands for the optical fiber sensing and microwave photonic systems.
Collapse
|
3
|
Woods J, Heath D, Daykin J, Sverre TC, Keenlyside B, Mills B, Sagnes I, Beaudoin G, Blin S, Garnache A, Tropper A, Apostolopoulos V. Semiconductor disk laser in bi-frequency operation by laser ablation micromachining of a laser mirror. OPTICS EXPRESS 2019; 27:22316-22326. [PMID: 31510527 DOI: 10.1364/oe.27.022316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 06/11/2019] [Indexed: 06/10/2023]
Abstract
We present bi-frequency continuous wave oscillation in a semiconductor disk laser through direct writing of loss-inducing patterns onto an intra-cavity high reflector mirror. The laser is a Vertical External Cavity Surface Emitting Laser which is optically pumped by up to 1.1 W of 808 nm light from a fibre coupled multi-mode diode laser, and oscillates on two Hermite-Gaussian spatial modes simultaneously, achieving wavelength separations between 0.2 nm and 5 nm around 995 nm. We use a Digital Micromirror Device (DMD) enabled laser ablation system to define spatially specific loss regions on a laser mirror by machining away the Bragg layers from the mirror surface. The ablated pattern is comprised of two orthogonal lines with the centermost region undamaged, and is positioned in the laser cavity so as to interact with the lasing mode, thereby promoting the simultaneous oscillation of the fundamental and a higher order spatial mode. We demonstrate bi-frequency oscillation over a range of mask gap sizes and pump powers.
Collapse
|
4
|
Li Y, Rolland A, Iwamoto K, Kuse N, Fermann M, Nagatsuma T. Low-noise millimeter-wave synthesis from a dual-wavelength fiber Brillouin cavity. OPTICS LETTERS 2019; 44:359-362. [PMID: 30644899 DOI: 10.1364/ol.44.000359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
In this Letter, a photonic system is proposed to generate millimeter waves with low phase noise and ultra-high frequency stability. By locking two free-running CW lasers to the same fiber cavity whose free-spectral range is actively stabilized, millimeter waves can be synthesized in a wide frequency range with fine-tuning capability. Exploiting the spectral narrowing effect of stimulated Brillouin scattering, the generated millimeter waves exhibit low phase noise that does not scale up as the frequency increases. In the experimental demonstration, up to ∼300 GHz millimeter waves are generated, with a phase noise of <-90 dBc/Hz at 10 kHz offset limited by the local oscillator and an in-loop 60 min frequency RMS drift of 0.43 mHz. The output frequency of the system can be readily increased to sub-THz region by replacing one of the pump CW lasers.
Collapse
|
5
|
A photonic frequency discriminator based on a two wavelength delayed self-heterodyne interferometer for low phase noise tunable micro/mm wave synthesis. Sci Rep 2018; 8:13719. [PMID: 30209321 PMCID: PMC6135791 DOI: 10.1038/s41598-018-31712-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 08/22/2018] [Indexed: 11/29/2022] Open
Abstract
Low phase noise frequency synthesizers are of paramount interest in many areas of micro-mm wave technology, encompassing for example advanced wireless communication, radar, radio-astronomy, and precision instrumentation. Although this broad research field is not bereft of methods for the generation of either low phase noise micro- or mm waves, no universal system applicable to low phase noise generation for micro and mm waves has yet been demonstrated. Here we propose a new photonic frequency discriminator based on a two wavelength delayed self-heterodyne interferometer which is compatible with such an objective. The photonic frequency discriminator can be a reference both for micro and mm waves to lower their phase noise. As a proof-of-concept, we demonstrate a low phase noise tunable OEO (6–18 GHz) and locking of a heterodyne beat between two cw lasers (10–400 GHz) with low relative phase noise. The required components for the photonic frequency discriminator are off-the-shelf and can be readily assembled. We believe this new type of photonic frequency discriminator will enable a new generation of universal precision tunable sources for the X, K, V, W and mm-bands and beyond.
Collapse
|
6
|
Kotlicki O, Scheuer J. Thermal self-stability, multi-stability, and memory effects in single-mode Brillouin fiber lasers. OPTICS EXPRESS 2017; 25:27321-27333. [PMID: 29092208 DOI: 10.1364/oe.25.027321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/10/2017] [Indexed: 06/07/2023]
Abstract
The main drawback of fiber lasers is their high sensitivity to fluctuation in the properties of their surroundings, where even a minuscule fluctuation in the ambient parameters can destabilize them. In this paper, a new passive feedback mechanism inherent to Brillouin fiber lasers (BFLs) is presented and studied. This mechanism, stemming from the interplay between thermal optical-length variations and the gain-line induced frequency dependent lasing power, triggers unexpected and counter-intuitive phenomena such as self-frequency-stabilization, multi-stability, and memory effects. This feedback sheds light on the dynamic behavior of BFLs and can be controlled and modified by engineered the gain lineshape.
Collapse
|
7
|
Xiang D, Lu P, Xu Y, Chen L, Bao X. Random Brillouin fiber laser for tunable ultra-narrow linewidth microwave generation. OPTICS LETTERS 2016; 41:4839-4842. [PMID: 28005844 DOI: 10.1364/ol.41.004839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Studies about random lasing phenomena taking place in disordered structures with amplification are gaining great interest, as they can support dual wavelength lasing without cavity length restriction and, hence, the tunable beat frequency in a microwave can be created in a random cavity and be amplified for applications in the information and communication technology. Here, we present a novel random Brillouin fiber laser scheme using the stimulated Brillouin scattering as gain and strong Rayleigh scattering feedback (10 km) in the single-mode fiber. The high degree of mutual coherence between the two Stokes beams from two different lasers leads to the generation of tunable ultra-narrow linewidth microwave signals (<10 Hz at 3 dB bandwidth) with a 70 dB contrast. This offers a simple and cost-effective design for microwave sources.
Collapse
|
8
|
Paquet R, Blin S, Myara M, Gratiet LL, Sellahi M, Chomet B, Beaudoin G, Sagnes I, Garnache A. Coherent continuous-wave dual-frequency high-Q external-cavity semiconductor laser for GHz-THz applications. OPTICS LETTERS 2016; 41:3751-3754. [PMID: 27519080 DOI: 10.1364/ol.41.003751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a continuous-wave highly-coherent and tunable dual-frequency laser emitting at two frequencies separated by 30 GHz to 3 THz, based on compact III-V diode-pumped quantum-well surface-emitting semiconductor laser technology. The concept is based on the stable simultaneous operation of two Laguerre-Gauss transverse modes in a single-axis short cavity, using an integrated sub-wavelength-thick metallic mask. Simultaneous operation is demonstrated theoretically and experimentally by recording intensity noises and beat frequency, and time-resolved optical spectra. We demonstrated a >80 mW output power, diffraction-limited beam, narrow linewidth of <300 kHz, linear polarization state (>45 dB), and low intensity noise class-A dynamics of <0.3% rms, thus opening the path to a compact low-cost coherent GHz to THz source development.
Collapse
|
9
|
Danion G, Frein L, Bacquet D, Pillet G, Molin S, Morvan L, Ducournau G, Vallet M, Szriftgiser P, Alouini M. Mode-hopping suppression in long Brillouin fiber laser with non-resonant pumping. OPTICS LETTERS 2016; 41:2362-2365. [PMID: 27177003 DOI: 10.1364/ol.41.002362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We propose a reliable method for stabilizing narrow linewidth Brillouin fiber lasers with non-resonant pumping. Mode-hopping is suppressed by means of a phase-locked loop that locks the pump-Stokes detuning to a local radio-frequency (RF) oscillator. Stable single-mode operation of a 110-m-long Brillouin fiber laser oscillating at 1.55 μm is demonstrated for several hours. The beat note between two independent Stokes waves presents a phase noise level of -60 dBc/Hz at 100 Hz with a -20 dB/decade slope, and a FWHM linewidth lower than 50 Hz.
Collapse
|
10
|
Danion G, Hamel C, Frein L, Bondu F, Loas G, Alouini M. Dual frequency laser with two continuously and widely tunable frequencies for optical referencing of GHz to THz beatnotes. OPTICS EXPRESS 2014; 22:17673-17678. [PMID: 25089387 DOI: 10.1364/oe.22.017673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A dual-frequency 1.55 µm laser for CW low noise microwave, millimeter and sub millimeter wave synthesis is demonstrated, where frequency stabilization is possible on each wavelength independently. The solid state Er:Yb laser output power is 7 mW. The amplitude noise is -150 dBc/Hz at 1 MHz offset frequency. In free running regime, the frequency noise is 3.10(5)/f Hz/sqrt(Hz) (800 Hz on a 1µs timescale), better than commercial fibered or semi-conductor sources at this wavelength.
Collapse
|
11
|
Watts R, Rosales R, Lelarge F, Ramdane A, Barry L. Mode coherence measurements across a 1.5 THz spectral bandwidth of a passively mode-locked quantum dash laser. OPTICS LETTERS 2012; 37:1499-1501. [PMID: 22555717 DOI: 10.1364/ol.37.001499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The mode coherence of adjacent and non-adjacent spectral modes of a passively mode locked quantum dash (QDash) semiconductor laser are deduced through radio frequency beat-tone linewidth measurements. A wavelength conversion scheme that uses degenerate four wave mixing in a semiconductor optical amplifier is proposed which considerably extends the mode spacing beyond the limit imposed by conventional fast-photodetection and electrical spectrum analysis of around 100 GHz. Using this scheme, the mode coherence of the QDash laser was measured out to the thirty-first harmonic, or a mode separation of 1.5 THz.
Collapse
Affiliation(s)
- Regan Watts
- The Rince Institute, School of Electronic Engineering, Dublin City University, Dublin 9, Ireland.
| | | | | | | | | |
Collapse
|