Mode-locking at very high repetition rates more than terahertz in passively mode-locked distributed-Bragg-reflector laser diodes

Arahira, S.; Matsui, Yasuhiro; Ogawa, Y.

doi:10.1109/3.517021

Cited by 161 publications

(60 citation statements)

References 26 publications

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“…It is notable that this type of modelocking does not require additional intracavity nonlinear elements such as saturable absorbers, or mode-selection elements, such as Bragg reflectors, that were used to achieve passive harmonic modelocking at THz repetition rates in other semiconductor lasers 20 . Rather, the modes are locked passively due to the behavior of the QCL gain medium itself.…”

Section: Several Techniques To Generate Optical Frequency Combs (Ofcsmentioning

confidence: 99%

Self-starting harmonic frequency comb generation in a quantum cascade laser

et al. 2017

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Optical frequency combs1,2 establish a rigid phase-coherent link between microwave and optical domains and are emerging as high-precision tools in an increasing number of applications 3 . Frequency combs with large intermodal spacing are employed in the field of microwave photonics for radiofrequency arbitrary waveform synthesis 4,5 and for generation of THz tones of high spectral purity in the future wireless communication networks 6,7 . We demonstrate for the first time self-starting harmonic frequency comb generation with a THz repetition rate in a quantum cascade laser. The large intermodal spacing caused by the suppression of tens of adjacent cavity modes originates from a parametric contribution to the gain due to temporal modulations of the population inversion in the laser 8,9 . The mode spacing of the harmonic comb is shown to be uniform to within 5 × 10 −12 parts of the central frequency using multiheterodyne self-detection. This new harmonic comb state extends the range of applications of quantum cascade laser frequency combs 10-13 . Several techniques to generate optical frequency combs (OFCs) have been demonstratedin the last decades based on different nonlinear mechanisms that fulfill the modelocking condition. Originally, passively modelocked lasers based on saturable absorption and Kerr lensing were used to create short light pulses, and were subsequently shown to also constitute frequency combs. This type of modelocking is an example of amplitude-modulated modelocking, so-named for the temporal behavior of the electric field of the emitted light. However, these techniques usually result in elaborate optical systems. More recently, new routes promising chip-scale comb generators have been investigated based on optically-pumped ultra-high-quality-factor crystalline microresonators 14-16 and on broadband quantum cascade lasers (QCLs) with specially designed multistage active regions 10,17 . In both cases the essential underlying mechanism responsible for the generation of OFCs is cascaded four-wave mixing (FWM) enabled by a third-order χ (3) Kerr nonlinearity. The temporal behavior of these OFCs is not restricted to ultrashort pulses but can represent rather sophisticated waveforms due to a non-trivial relationship among the spectral phases of the comb teeth. In fact, the output of a QCL-based frequency comb resembles that of a frequency-modulated laser with nearly constant output intensity 10,18 .A novel mechanism of OFC generation in QCLs was suggested by the recent discovery of a new laser state 19 , which comprises many modes separated by higher harmonics of the 2 cavity free spectral range (FSR) (Figure 1a). This spectrum radically differs from that of fundamentally modelocked QCL combs where adjacent cavity modes are populated ( Figure 1b THz repetition rates in other semiconductor lasers 20 . Rather, the modes are locked passively due to the behavior of the QCL gain medium itself.In this work we employed two Fabry-Perot (FP) QCLs fabricated from the same growth process with 6 mm-long cavit...

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Section: Several Techniques To Generate Optical Frequency Combs (Ofcsmentioning

confidence: 99%

Self-starting harmonic frequency comb generation in a quantum cascade laser

et al. 2017

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“…One of the distinct ways of achieving higher ML frequencies is to introduce harmonic mode-locking (HML) techniques. A HML laser produces an optical pulse train at an integer multiple of the fundamental round-trip frequency of the device, which can be achieved using sub-harmonic optical injection [2], colliding pulse ML (CPM) [3], or compound-cavity ML (CCM) methods [4,5]. Frequencies of up to 1.5 THz have been achieved with the use of CCM effects in distributed Bragg reflector (DBR) lasers [4], albeit operating over a narrow range of bias conditions and with limited reproducibility.…”

Section: Introductionmentioning

confidence: 99%

“…A HML laser produces an optical pulse train at an integer multiple of the fundamental round-trip frequency of the device, which can be achieved using sub-harmonic optical injection [2], colliding pulse ML (CPM) [3], or compound-cavity ML (CCM) methods [4,5]. Frequencies of up to 1.5 THz have been achieved with the use of CCM effects in distributed Bragg reflector (DBR) lasers [4], albeit operating over a narrow range of bias conditions and with limited reproducibility. The most extensive demonstration of HML used purpose-built AlGaAs/GaAs CCM Fabry-Perot (FP) lasers incorporating an intra-cavity reflector (ICR), where repetition frequencies up to 2.1 THz were demonstrated at 850 nm [5].…”

Section: Introductionmentioning

confidence: 99%

Mode-locking and frequency mixing at THz pulse repetition rates in a sampled-grating DBR mode-locked laser

Hou¹,

Haji²,

Marsh³

2014

Opt. Express

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Abstract:We report a sampled grating distributed Bragg reflector (SGDBR) laser with two different gratings which mode-lock independently at respective pulse repetition frequencies of 640 and 700 GHz. The device operates in distinct regimes depending on the bias conditions, with stable pulse trains observed at 640 GHz, 700 GHz, the mean repetition frequency of 666 GHz, and the sum frequency of 1.34 THz (due to nonlinear mixing). Performance is consistent and highly reproducible with exceptional stability observed over wide ranges of drive bias conditions. Furthermore, a monolithically integrated semiconductor optical amplifier is used to amplify the pulse trains, providing an average output power of 46 mW at 666 GHz.

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“…There has been growing interest in the passive mode locking of monolithic semiconductor lasers to produce higher repetition frequency light sources than allowed by the electrical modulation. High repetition frequencies ranging from hundreds of GHz up to more than THz with sub-picosecond pulses have been demonstrated by shortening the cavity length [1], by employing multiple colliding pulse mode-locking [2], or by employing harmonic mode-locking [3]. Compact in size and self-aligned, the passively mode-locked laser diode operating at 20-100 GHz frequency has potential of the light source without electrical parasitic limitations in the wavelength division multiplexing (WDM) system.…”

Section: Gradual Suppression Of Nearest Modes When Approaching Cpm Opmentioning

confidence: 99%

Ultrashort Pulse, Monolithic Modelocked Lasers for WDM Systems

Dapkus¹

2001

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Mode-locking at very high repetition rates more than terahertz in passively mode-locked distributed-Bragg-reflector laser diodes

Cited by 161 publications

References 26 publications

Self-starting harmonic frequency comb generation in a quantum cascade laser

Self-starting harmonic frequency comb generation in a quantum cascade laser

Mode-locking and frequency mixing at THz pulse repetition rates in a sampled-grating DBR mode-locked laser

Ultrashort Pulse, Monolithic Modelocked Lasers for WDM Systems

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