Injection-locking of a fiber-pigtailed high-power laser to an external cavity diode laser via a fiber optic circulator

Abstract

We report a simple tunable master-slave laser injection-lock scheme for atomic physics experiments. Seed light from an external cavity diode laser is injected into a high-power fiber-pigtailed diode laser via a fiber optic circulator. High-power outputs (up to ∼600 mW) at the injected frequency have been obtained in a singlemode fiber with tuning over a wide wavelength range (∼15 nm). The scheme is simpler and more cost-effective than the traditional scheme of free-space injectionlocking. PACS numbers: Valid PACS appear hereTunable single frequency external cavity diode lasers (ECDLs) are widely used in atomic physics experiments. 1 Typically, 100 mW of output power can be obtained from an ECDL. When higher powers are required, master-slave setups based on injection-locking are frequently used to reach higher power output while maintaining the tuning and linewidth characteristics of the ECDL. In these systems, typically seed light from a master laser is coupled via free space into a slave laser, with the combination of a Faraday rotator and a polarizing beamsplitter acting to separate the amplified beam from the injected beam. 2 Such free-space injection-locking, however, is often susceptible to unlocking of the slave laser from the injected frequency. The success of the injection locking depends on the mode matching between the seed beam and the slave diode, on the in-coupled seed power, and on the matching between the seed frequency and the internal cavity resonance of the seed laser. Changes in the operating conditions over time can result in unreliable locking of the slave diode. An interesting and practical approach to circumvent such unlocking has been reported recently. 3 Alternatively, tapered amplifiers (TAs) can also be used to boost the available power. The power available from a TA depends on the wavelength, and is quite high at a few commonly-used wavelengths such as 850 nm. However, the range of wavelengths accessible with TAs is limited, their cost is substantial, and they often require free-space coupling as well. In addition, the beam quality obtained from a TA is often poor, leading to a low coupling efficiency of the TA output beam to a single-mode optical fiber.In this paper, we demonstrate a simple scheme to obtain moderate powers, up to 600 mW at 980 nm, of tunable single-frequency laser light directly in an optical fiber. Our scheme uses a fiber-pigtailed laser diode as a slave laser, injection-locked by a seed from an ECDL via a fiber optic circulator. Injection-locking via a fiber optic circulator has been demonstrated at 1550 nm previously. 4 However, this approach has not, to our knowledge, been used before in visible or near infrared wavelengths. Recently, it has become possible to obtain fiber optic circulators for shorter wavelengths, with specifications comparable to those for free-space isolators. By using a fiber optic circulator, we eliminate most of the free-space components involved in a typical injection locking setup, and hence reduce the alignment sensitivity. The only free-...

Theoretical Study on Dual-Function Optical Phased Array of LiDAR and Optical Wireless Communication Based on Optically Injection-Locked Semiconductor Lasers

“…Therefore, the dual-function OPA system, using OIL semiconductor lasers, can ensure high OWC performance in side lobes under different LiDAR operation conditions. In addition, the OIL-based OPA offers power scaling capabilities due to the high output power of active emitters, specifically OIL lasers [22], which ensure excellent OWC performance in side lobes for various application ranges. For example, the proposed 21-element OPA, with an output power of 10 dBm per OIL semiconductor laser, will emit a total output power of 23.5 dBm, with the estimated power in the main beam at 20 dBm.…”

“…As per the assigned 20 dB SLL, the transmitted power in side lobes for OWC applications is 0 dBm, making it suitable for indoor or short-range OWC applications [23]. High-performance requirements for long-range OWC applications can be achieved by using high-power semiconductor lasers (hundreds of milliwatts) [22], adding optical amplifiers, and utilizing high-sensitivity photodetectors at receivers. Consequently, the dual-function OPA based on OIL semiconductor lasers can achieve high performance of the OWC function in the side lobe region while maintaining the primary LiDAR function in the main lobe.…”

Continuous production of rovibronic-ground-state RbCs molecules via short-range photoassociation to thebΠ13–cΣ1+Shimasaki1, Kim2, Zhu3 et al. 2018Phys. Rev. ASelf Cite120100View full textAdd to dashboardCite

“…We irradiate the atom clouds with a PA laser, which associates pairs of colliding Rb and Cs atoms into an excited RbCs molecular state. For this PA transition, we use up to 600 mW from a diode laser, which was set up in a fiber-based master-slave system [25]. The master laser, which consists of a 980 nm diode laser in an external cavity diode laser (ECDL) configuration, can be tuned from 10120 cm −1 to 10350 cm −1 .…”