Query: Directly pumped 10 GHz microcomb modules from low power diode lasers

Candidate papers:

abstract: Soliton microcombs offer the prospect of advanced optical metrology and timing systems in compact form factors. In these applications, the pumping of microcombs directly from a semiconductor laser without amplification or triggering components is desirable to reduce system power and to simplify system design. At the same time, low repetition rate microcombs are required in many comb applications as an interface to detectors and electronics, but their increased mode volume makes them challenging to pump at low power. Here 10 GHz repetition rate soliton microcombs are directly pumped by low power <20 mW) diode lasers. High Q silica microresonators are used for this low power operation and are packaged into fiber connectorized modules that feature temperature control for improved long term frequency stability.
author_names: Myoung-Gyun Suh

Christine Y Wang

Cort N Johnson

Kerry J Vahala
title: Directly pumped 10 GHz microcomb modules from low power diode lasers.
venue: Optics letters
year: 2019

abstract: Microcombs provide a path to broad bandwidth integrated frequency combs with low power consumption, which are compatible with wafer scale fabrication. Yet, electrically driven, photonic chip based microcombs are inhibited by the required high threshold power and the frequency agility of the laser for soliton initiation. Here we demonstrate an electrically driven soliton microcomb by coupling a III V material based (indium phosphide) multiple longitudinal mode laser diode chip to a high Q silicon nitride microresonator fabricated using the photonic Damascene process. The laser diode is self injection locked to the microresonator, which is accompanied by the narrowing of the laser linewidth, and the simultaneous formation of dissipative Kerr solitons. By tuning the laser diode current, we observe transitions from modulation instability, breather solitons, to single soliton states. The system operating at an electronically detectable sub 100 GHz mode spacing requires less than 1 Watt of electrical power, can fit in a volume of ca. 1 cm3, and does not require on chip filters and heaters, thus simplifying the integrated microcomb.Chip based frequency combs promise many applications, but full integration requires the electrical pump source and the microresonator to be on the same chip. Here, the authors show such integration of a microcomb with 100 GHz mode spacing without additional filtering cavities or on chip heaters.
author_names: Arslan S Raja

Andrey S Voloshin

Hairun Guo

Sofya E Agafonova

Junqiu Liu

Alexander S Gorodnitskiy

Maxim Karpov

Nikolay G Pavlov

Erwan Lucas

Ramzil R Galiev

Artem E Shitikov

John D Jost

Michael L Gorodetsky

Tobias J Kippenberg
title: Electrically pumped photonic integrated soliton microcomb
venue: Nature Communications
year: 2019

abstract: In conclusion, we have built and characterized a SCOWA based system that produces low noise, 10 GHz pulse trains with output power up to 0.39 W, with an external amplification stage, using only electrically pumped diodes. The timing jitter is ~6 fs. Given that the shot noise can potentially be reduced if the total output power is considered, the timing jitter integrated to the Nyquist frequency can be as low as ~7 8 with the current mode locked laser.
author_names: Josue Davila-Rodriguez

C Williams

Peter J Delfyett

Jason Plant

Paul W Juodawlkis
title: All diode generation and amplification of 10 GHz pulse trains from coupled cavity mode locked lasers using Slab Coupled Waveguide Amplifiers
venue: IEEE Avionics, Fiber Optics and Photonics Digest CD
year: 2012

abstract: We demonstrate the first self referenced full stabilization of a diode pumped solid state laser (DPSSL) frequency comb with a GHz repetition rate. The Yb:CALGO DPSSL delivers an average output power of up to 2.1 W with a typical pulse duration of 96 fs and a center wavelength of 1055 nm. A carrier envelope offset (CEO) beat with a signal to noise ratio of 40 dB (in 10 kHz resolution bandwidth) is detected after supercontinuum generation and f to 2f interferometry directly from the output of the oscillator, without any external amplification or pulse compression. The repetition rate is stabilized to a reference synthesizer with a residual integrated timing jitter of 249 fs [10 Hz 1 MHz] and a relative frequency stability of 10 12/s. The CEO frequency is phase locked to an external reference via pump current feedback using home built modulation electronics. It achieves a loop bandwidth of ~150 kHz, which results in a tight CEO lock with a residual integrated phase noise of 680 mrad [1 Hz 1 MHz] We present a detailed characterization of the GHz frequency comb that combines a noise analysis of the repetition rate frep, of the CEO frequency fCEO, and of an optical comb line at 1030 nm obtained from a virtual beat with a narrow linewidth laser at 1557 nm using a transfer oscillator. An optical comb linewidth of about 800 kHz is assessed at 1 s observation time, for which the dominant noise sources of frep and fCEO are identified.
author_names: Sargis Hakobyan

Valentin Johannes Wittwer

Pierre Brochard

Kutan Gurel

Stephane Schilt

Aline S Mayer

Ursula Keller

Thomas Sudmeyer
title: Full stabilization and characterization of an optical frequency comb from a diode pumped solid state laser with GHz repetition rate.
venue: Optics express
year: 2017

abstract: Pulses as short as 8.1 fs were generated from a blue laser diode pumped Kerr lens mode locked Ti:sapphire oscillator, with an average power of 27 mW and a repetition rate of 120.6 MHz. The full width at half maximum exceeds 146 nm, benefitting from the dispersion management by a combination of a low dispersion fused silica prism pair and a series of double chirped mirrors. To the best of our knowledge, this is the first time to generate sub 10 fs pulses from a laser diode directly pumped Ti:sapphire oscillator.
author_names: Han Liu

Geyang Wang

Jianwang Jiang

Wenlong Tian

Dacheng Zhang

Hainian Han

Shaobo Fang

Jiangfeng Zhu

Zhiyi Wei
title: Sub 10 fs pulse generation from a blue laser diode pumped Ti:sapphire oscillator
year: 2020

abstract: Photonics chip based soliton microcombs have been used in many applications including LIDAR, spectroscopy, coherent communication and astronomical spectrometer calibration [1] Current initiated soliton microcombs have been demonstrated [2, 3] recently, signifying improvements in the fabrication of high Q Si3N4 microresonators. However, both approaches suffer from limited input laser power, thus only demonstrated single soliton at repetition rates above 149 GHz, which are challenging to detect with commercially available photodetectors. Here we demonstrate a single soliton generation in 100 GHz FSR Si3N4 microresonators fabricated using the photonic Damascene reflow process [4] yielding the intrinsic Q factor exceeding 15 million [5] Using a compact hybrid laser with narrow linewidth, low relative intensity noise 160 dBc/Hz at foffset=100 kHz) and high output power up to 100 mW [6] different comb states are observed by simply changing the current of the laser diode, without the need of complex tuning mechanism such as a single sideband modulator [7] As the laser noise is directly transferred to the soliton comb line, this low noise laser can be utilized in applications where the phase noise is a critical parameter, e.g. low noise microwave generation or coherent communication. The experimental setup shown in Fig. 1 (a) consists of an ULN laser operated by a current source and temperature controllers to tune its frequency and power. After the light is coupled into the Si3N4 photonic chip via double inverse nano tapers [8] the temperature of FBG/GC is changed to align the laser wavelength to the resonance of the microresonator. The laser diode current is increased 330 mA) until soliton existence range is sufficiently long. This is indicated by transmission signal directly observed after the chip on the photodetector (Fig. 1 c) Due to high Q factor of the Si3N4, the soliton state can be accessed via simply frequency forward tuning [9] without the need of any complex soliton tuning mechanism. Further, different comb states are observed, i.e. modulation instability, multi soliton state and single soliton state, via laser diode current tuning. The coherence properties of the soliton comb teeth is asserted by performing a heterodyne beatnote measurement using a reference laser with a short time linewidth of 10 kHz (Fig. 1b) The soliton spectrum is fitted with a sech2 function corresponding to a 3 dB bandwidth of 19.3 nm and a 131.5 fs pulse.
author_names: Arslan S Raja

Junqiu Liu

Nicolas Volet

Rui Wang

Jijun He

Erwan Lucas

Romain Bouchand

Paul Adrian Morton

John E Bowers

Tobias J Kippenberg
title: Photonic Chip Based Soliton Microcomb Driven by a Compact Ultra Low Noise Laser
venue: 2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)
year: 2019

abstract: Single frequency stable, narrow linewidth diode pumped solid state (DPSS) lasers are commonly used in many applications and science areas, like high resolution spectroscopy, optical metrology, gravity wave detection [1] fundamental physics and others. Many of them require optical amplification of the DPSS seed laser to obtain higher output power while maintaining the excellent optical properties of the laser beam (e.g. Coherent Power Summation for military applications) In Ref.[2] the miniature, single frequency stable DPSS laser operating at 1064 nm and patented structure of the monolithic microchip resonator Nd:YVO4/YVO4/YVO4 were described (Fig.1a) However, from commercial point of view the DPSS seed laser needs to be inexpensive, mechanically and optically stable for wide temperature range, easy to assemble and service. Here, the comparison of the 0.3 mm long a cut Nd:YVO4 crystal resonator (Fig. 1b) with dielectric mirrors directly deposited onto the outer crystal surfaces (short resonator SR) and described in Ref.[3] the 8.5mm long microchip resonator Nd:YVO4/YVO4/YVO4 (long resonator LR) is presented for the first time. Both resonators were examined in the same DPSS laser module, providing the same conditions for their operation and they were pumped through a 3.5 mm long GRIN lens collimator (Casix) by a linearly polarized 1W multimode 808 nm laser diode (QA 808 1000 030, Axcel Photonics) In comparison to the LR, the SR configuration provides only 27% less power conversion efficiency (at only 0.3mm resonator/gain crystal thickness) due to back reflection from HR@808nm coating of the pump beam. However, for the 808 nm pump power lower than 250 mW, the SR ensures slightly more output power than LR configuration due to 10 times lower power threshold (Fig. 1c) The pure single longitudinal mode operation was obtained for both configurations (Fig. 1e) nonetheless the SR provides almost 9 times wider temperature range (14 32 degC 550mW of pump power) where laser resonator works in single mode (SM) regime (Fig. 1d) than the LR chip (21.2 23.2 degC 550mW of pump power) Additionally, the SR configuration does not need a crystals bonding process and it is around 25% cheaper (excluding bonding costs) compared to the LR. Whereas, the output beam divergence becomes around 4 times higher for the SR and it is more sensitive to angular aligning of the pump beam causing that transverse mode distribution can occur. Presented results and comparison were carried out within a commercial TANGO project "Development, optimization and integration of the single frequency seed laser operating at 1064 nm with medium power fiber amplifier" (TANGO1/266345/NCBR/2015) financed by National Centre for Research and Development (NCBiR) Poland and statutory funds of the Faculty of Electronics (0401/0030/18)
author_names: Grzegorz Dudzik

Karol Krzempek

Krzysztof M Abramski
title: Comparison of Nd:YVO4 Based Monolithic Microchip Laser Resonators for Single Frequency Stable, CW Diode Pumped Laser Sources
venue: 2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)
year: 2019

abstract: An all diode pumped Nd:YAG burst mode laser was demonstrated. A diode laser side pumped Nd:YAG laser with Qswitcher, as laser oscillator, was employed to produce burst pulse directly. When the diode laser worked at 10Hz and Qswitcher was operated at 10kHz, a maximum burst energy of 456mJ was obtained in the master oscillator with the highest optical efficiency of ~30% Each burst included 19 pulses in the pumping duration of 2ms. A master oscillator and power amplifier architecture was adapted to scale the burst energy to meet PLIF system applications. The burst energy of 456mJ obtained from laser oscillator was amplified to 2.2J by use of three diode laser side pumped Nd:YAG modules as laser amplifiers. The energy extraction efficiency of each stage was achieved to ~13% ~22% and ~24% respectively. The single pulse energy of 1064nm laser at 10 kHz reached to ~116 mJ with pulse width of 9.8 ns and a peak power of ~11.8 MW. The performances of pulse burst laser we constructed can be better and improved greatly by use of more amplifiers.
author_names: Xudong Li

Guichuan Xu

Renpeng Yan

Wentao Wu

Zhixiang Liu

Xiaolin Wen

Deying Chen
title: A 2.2J all diode pumped Nd:YAG burst mode laser at repetition rate of 10kHz
venue: Other Conferences
year: 2018

abstract: Broad area lasers with narrow spectra are required for many pumping applications and for wavelength beam combination. Although monolithically stabilized lasers show high performance, some applications can only be addressed with external frequency stabilization, for example when very narrow spectra are required. When conventional diode lasers with vertical far field angle, ThV 95% 45deg (95% power) are stabilized using volume holographic gratings (VHGs) optical losses are introduced, limiting both efficiency and reliable output power, with the presence of any bar smile compounding the challenge. Diode lasers with designs optimized for extremely low vertical divergence (ELOD lasers) directly address these challenges. The vertical far field angle in conventional laser designs is limited by the waveguiding of the active region itself. In ELOD designs, quantum barriers are used that have low refractive index, enabling the influence of the active region to be suppressed, leading to narrow far field operation from thin vertical structures, for minimal electrical resistance and maximum power conversion efficiency. We review the design process, and show that 975 nm diode lasers with 90 mm stripes that use ELOD designs operate with ThV 95% 26deg and reach 58% power conversion efficiency at a CW output power of 10 W. We demonstrate directly that VHG stabilized ELOD lasers have significantly lower loss and larger operation windows than conventional lasers in the collimated feedback regimes, even in the presence of significant 1 mm) bar smile. We also discuss the potential influence of ELOD designs on reliable output power and options for further performance improvement.
author_names: P A Crump

Steffen Knigge

Andre Maassdorf

Frank Bugge

Stefan Hengesbach

Ulrich Witte

Hans Dieter Hoffmann

Bernd Kohler

Ralf Hubrich

Heiko Kissel

Jens Biesenbach

Gotz Erbert

Guenther Traenkle
title: Low loss smile insensitive external frequency stabilization of high power diode lasers enabled by vertical designs with extremely low divergence angle and high efficiency
venue: Photonics West Lasers and Applications in Science and Engineering
year: 2013

abstract: It is widely known that a diode pumped solid state laser (DPSSL) has very limited modulation bandwidth. Recently, we directed our attention toward the opportunities for directly modulating a DPSSL to generate high speed green light signals, with high power and superior beam quality, which are highly desirable in underwater wireless optical communication. The constraint imposed by the limited modulation bandwidth of a DPSSL is circumvented with the strategy of orthogonal frequency division multiplexing and power loading. With a compact DPSSL dismantled from a low cost laser pointer, we achieve net bit rates of 108.55 Mb/s for the 64 quadrature amplitude modulation (QAM) signal at a bit error rate (BER) of 6.42x10 4 and 89.55 Mb/s for the 32 QAM signal at a BER of 4.81x10 4, respectively, over a 2 m underwater channel. When the underwater transmission distance is increased to 6 m, the BERs are still below the forward error correction (FEC) limit of 3.8x10 3.
author_names: Jing Xu

Meiwei Kong

Aobo Lin

Yuhang Song

Jun Han

Zhiwei Xu

Bo Wu

Shiming Gao

Ning Deng
title: Directly modulated green light diode pumped solid state laser for underwater wireless optical communication.
venue: Optics letters
year: 2017