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  • Publication
    Accès libre
    Carrier-Envelope Offset Frequency Stabilization of a Fiber Laser by Cross Gain Modulation
    We present the first carrier-envelope offset (CEO) frequency stabilization of a fiber laser by cross gain modulation. The Yb-doped fiber laser is mode-locked by nonlinear polarization evolution and emits 32-nm wide dissipative solitons at a repetition rate of 125 MHz with 150 mW of average output power. A continuous wave laser signal at a wavelength of 1025 nm is used as an intracavity power modulator. A low power of only 200 μW of modulator signal is coupled into the fiber laser and amplified in the gain segment. This signal cross modulates the laser gain, achieving 40 times larger modulation bandwidth of the intracavity laser power than with standard pump-current control. A tight CEO lock is demonstrated with 361 mrad of residual integrated phase noise (from 1 Hz to 1 MHz). The method allows easy implementation in many existing fiber laser frequency combs based on various saturable absorbers and fiber configurations.
  • Publication
    Accès libre
    Frequency Comb Stabilization of Ultrafast Lasers by Opto-Optical Modulation of Semiconductors
    Gürel, Kutan
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    Wittwer, Valentin Johannes
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    In this paper, we review the current state and discuss new developments in opto-optical modulation (OOM) of semiconductor elements for frequency comb self-referenced stabilization of ultrafast lasers. This method has been successfully used for carrier-envelope offset (CEO) frequency stabilization of diodepumped solid-state lasers operating in 1-μm and 1.5-μm regimes, providing high feedback bandwidth and resulting in low noise performance. We compare the achieved results for Er- and Yb-based laser materials and in different regimes of repetition rates up to 1 GHz. In addition, we present the first semiconductor OOM for CEO stabilization in an ultrafast fiber laser. Moreover, we discuss requirements and design guidelines for OOM chips. In most demonstrations, semiconductor saturable absorber mirrors have been used for OOM, which in parallel were also responsible for pulse formation. By separating the OOM functionality from the pulse formation, we expect that it will enable low-noise CEO stabilization in other types of ultrafast lasers, such as, for example, high-power Kerr-lens mode-locked thin disk lasers.
  • Publication
    Accès libre
    Carrier-Envelope Offset Stabilized Ultrafast Diode-Pumped Solid-State Lasers
    Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs) have become an attractive alternative with state-of-the-art performance. In this article, we review the main achievements in ultrafast DPSSLs for frequency combs. We present the current status of carrier-envelope offset (CEO) frequency-stabilized DPSSLs based on various approaches and operating in different wavelength regimes. Feedback to the pump current provides a reliable scheme for frequency comb CEO stabilization, but also other methods with faster feedback not limited by the lifetime of the gain material have been applied. Pumping DPSSLs with high power multi-transverse-mode diodes enabled a new class of high power oscillators and gigahertz repetition rate lasers, which were initially not believed to be suitable for CEO stabilization due to the pump noise. However, this challenge has been overcome, and recently both high power and gigahertz DPSSL combs have been demonstrated. Thin disk lasers have demonstrated the highest pulse energy and average power emitted from any ultrafast oscillator and present a high potential for the future generation of stabilized frequency combs with hundreds of watts average output power.