Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPlaticon microcomb generation using laser self-injection locking
93
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The past decade has witnessed major advances in the development of microresonator-based frequency combs (microcombs) that are broadband optical frequency combs with repetition rates in the millimeter-wave to microwave domain. Integrated microcombs can be manufactured using wafer-scale process and have been applied in numerous applications. Most of these advances are based on the harnessing of dissipative Kerr solitons (DKS) in optical microresonators with anomalous group velocity dispersion (GVD). However, microcombs can also be generated with normal GVD using dissipative localized structures that are referred to as dark pulse, switching wave or platicon. Importantly, as most materials feature intrinsic normal GVD, the requirement of dispersion engineering is significantly relaxed for platicon generation. Therefore while DKS microcombs require particular designs and fabrication processes, platicon microcombs can be readily built using standard CMOS-compatible platforms such as thin-film (i.e. typically below 300 nm) Si3N4. Yet laser self-injection locking that has been recently used to create highly compact integrated DKS microcomb modules has not been demonstrated for platicons. Here we report the first fully integrated platicon microcomb operating at a microwave-K-band repetition rate. Using laser self-injection locking of a DFB laser edge-coupled to a Si3N4 microresonator, platicons are electrically initiated and stably maintained, enabling a compact microcomb module without any complex control. We further characterize the phase noise of the platicon repetition rate and the pumping laser. The observation of self-injection-locked platicons facilitates future wide adoption of microcombs as a build-in block in standard photonic integrated architectures via commercial foundry service.
rate research
Read More
Self-injection locking is a dynamic phenomenon representing stabilization of the emission frequency of an oscillator with a passive cavity enabling frequency filtered coherent feedback to the oscillator cavity. For instance, self-injection locking of a semiconductor laser to a high-quality-factor (high-Q) whispering gallery mode (WGM) microresonator can result in multiple orders of magnitude reduction of the laser linewidth. The phenomenon was broadly studied in experiments, but its detailed theoretical model allowing improving the stabilization performance does not exist. In this paper we develop such a theory. We introduce five parameters identifying efficiency of the self-injection locking in an experiment, comprising back-scattering efficiency, phase delay between the laser and the high-Q cavities, frequency detuning between the laser and the high-Q cavities, the pump coupling efficiency, the optical path length between the laser and the microresonator. Our calculations show that the laser linewidth can be improved by two orders of magnitude compared with the case of not optimal self-injection locking. We present recommendations on the experimental realization of the optimal self-injection locking regime. The theoretical model provides deeper understanding of the self-injection locking and benefits multiple practical applications of self-injection locked oscillators.
The Terahertz or millimeter wave frequency band (300 GHz - 3 THz) is spectrally located between microwaves and infrared light and has attracted significant interest for applications in broadband wireless communications, space-borne radiometers for Earth remote sensing, astrophysics, and imaging. In particular optically generated THz waves are of high interest for low-noise signal generation. In particular optically generated THz waves are of high interest for low-noise signal generation. Here, we propose and demonstrate stabilized terahertz wave generation using a microresonator-based frequency comb (microcomb). A unitravelling-carrier photodiode (UTC-PD) converts low-noise optical soliton pulses from the microcomb to a terahertz wave at the solitons repetition rate (331 GHz). With a free-running microcomb, the Allan deviation of the Terahertz signal is 4.5*10^-9 at 1 s measurement time with a phase noise of -72 dBc/Hz (-118 dBc/Hz) at 10 kHz (10 MHz) offset frequency. By locking the repetition rate to an in-house hydrogen maser, in-loop fractional frequency stabilities of 9.6*10^-15 and 1.9*10^-17 are obtained at averaging times of 1 s and 2000 s respectively, limited by the maser reference signal. Moreover, the terahertz signal is successfully used to perform a proof-of-principle demonstration of terahertz imaging of peanuts. Combining the monolithically integrated UTC-PD with an on-chip microcomb, the demonstrated technique could provide a route towards highly stable continuous terahertz wave generation in chip-scale packages for out-of-the-lab applications. In particular, such systems would be useful as compact tools for high-capacity wireless communication, spectroscopy, imaging, remote sensing, and astrophysical applications.
We present a simple and effective method to implement an active stabilization of a diode laser with injection locking, which requires minimal user intervenes. The injection locked state of the diode laser is probed by a photodetector, of which sensitivity is enhanced by a narrow laser-line filter. Taking advantage of the characteristic response of laser power to spectral modes from the narrow laser-line filter, we demonstrate that high spectral purity and low intensity noise of the diode can be simultaneously maintained by an active feedback to the injected laser. Our method is intrinsically cost-effective, and does not require bulky devices, such as Fabry-Perot interferometers or wavemeters, to actively stabilize the diode laser. Based on successful implementation of this method in our quantum gas experiments, it is conceivable that our active stabilization will greatly simplify potential applications of injection locking of diode lasers in modularized or integrated optical systems.
In this work, we describe an updated version of single arm locking, and the noise amplification due to the nulls can be flexibly restricted with the help of optical frequency comb. We show that, the laser phase noise can be divided by a specific factor with optical frequency comb as the bridge. The analytical results indicate that, the peaks in the science band have been greatly reduced. The performance of the noise suppression shows that the total noise after arm locking can well satisfy the requirement of time delay interferometry, even with the free-running laser source. We also estimate the frequency pulling characteristics of the updated single arm locking, and the results suggest that the pulling rate can be tolerated, without the risk of mode hopping. Arm locking will be a valuable solution for the noise reduction in the space-borne GW detectors. We demonstrate that, with the precise control of the returned laser phase noise, the noise amplification in the science band can be efficiently suppressed based on the updated single arm locking. Not only our method allows the suppression of the peaks, the high gain, low pulling rate, it can also serve for full year, without the potential risk of locking failure due to the arm length mismatch. We finally discuss the unified demonstration of the updated single arm locking, where both the local and the returned laser phase noises can be tuned to generate the expected arm-locking sensor actually. Our work could provide a powerful method for the arm locking in the future space-borne GW detectors.
Injection locking is a well known and commonly used method for coherent light amplification. Usually injection locking is done with a single-frequency seeding beam. In this work we show that injection locking may also be achieved in the case of multi-frequency seeding beam when slave laser provides sufficient frequency filtering. One relevant parameter turns out to be the frequency detuning between the free running slave laser and each injected frequency component. Stable selective locking to a set of three components separated of $1.2,$GHz is obtained for (positive) detuning values between zero and $1.5,$GHz depending on seeding power (ranging from 10 to 150 microwatt). This result suggests that, using distinct slave lasers for each line, a set of mutually coherent narrow-linewidth high-power radiation modes can be obtained.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
