Widely tunable, narrow linewidth external-cavity gain chip laser for spectroscopy between 10 – 11 µm

Abstract

Abstract:We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference. 175-210 (2012). 18. List of parts and instruments. We used an Innolume GM-1060-150-PM-250 gain module, a Thorlabs C240TME-1064 mounted aspheric lens, a Thorlabs GR13-1210 blazed diffraction grating, a Thorlabs KMSS/M kinematic mirror mount, a Thorlabs PA4FKW piezo chip, European Thermodynamics APH-127-10-25-S TEC modules, an Epcos S861 thermistor, and an AFW Technologies PISO-83-2-C-7-2-FB polarization maintaining in-fibre isolator in the construction of the laser. The laser was controlled using a custom-built current controller, ILX Lightwave LDT-5100 temperature controllers, and a PiezoDrive PDu-150CL piezo driver. The laser was frequency stabilised using a Brimrose TEM-250-50-10-2FP fibre-coupled AOM, an SRS SR510 lock-in amplifier, and a custom-built PI controller.

Advances in narrow linewidth diode lasers

“…Many scientific research institutes, such as Hanover University of Germany, University of Jena [48], Suleiman Demirel University of Turkey, and Australian National University, have carried out research reports on Littrow structure external cavity semiconductor laser. In 2016, Shin et al [49] from the Australian National University proposed that Littrow-ECL consist of a gain chip with one-sided tilt output light and a blazed grating (1200 lines/mm) to achieve an output power of 300 mW at 600 mA, wide tuning in the range of 100 nm near the 1080 nm band, a Lorentz line width of 4.2 kHz at 22.5 ms, and an excellent wavelength stability (40 kHz for 11 h). In the same year, the side-of-fringe stabilization technology was adopted by Suleiman Demirel University in Turkey [50] to achieve active frequency stabilization of ECL.…”

Advances in narrow linewidth diode lasers

“…选用衍射光栅作为反馈元件的外腔激光器通常会采用 Littrow 或 Littman 结构 [47] , 这两种结构 外腔激光器的谐振腔通常由半导体激光芯片、光学透镜或反射镜、闪耀光栅或者全息光栅等光学元件 [48] 、 土耳其苏莱曼 • 德米雷尔大学 (Suleiman Demirel University of Turkey)、澳大利亚国立大学 (Australian National University) 等多家科研机构对其进行了研究报道. 2016 年, 澳大利亚国立大学的 Shin 等 [49] 提出采用单边倾斜出光的增益芯片和闪耀光栅 (1200 线/mm) 构成 Littrow-ECL, 实现输出功率 300 mW@600 mA, 在 1080 nm 波段附近 100 nm 范围的宽调谐, 洛伦兹线宽 4.2 kHz@22.5 ms, 同时获 得优良的波长稳定性 (40 kHz@11 h). 同年, 土耳其苏莱曼 • 德米雷尔大学 [50] 采用一种 side-of-fringe 稳定技术, 实现了频率主动稳定 ECL, 其波长调谐范围为 60 nm (1000∼1060 nm), 线宽由 160 KHz 窄 化为 400 Hz.…”

High-Q-Factor Silica-Based Racetrack Microring Resonators

“…With the development of ultrahigh-speed optical interconnection, coherent optical communication [1][2][3], and coherent detection technology [4][5][6][7], more urgent requirements are put forward for the narrow linewidth, high power, and high stability of laser source. However, limited to the length of cavity, the spectral linewidth conventional distributed feedback (DFB) lasers and distributed bragg reflector (DBR) lasers are typically in the order of~MHz, along with a small tuning range around a few nm [8,9].…”

“…Therefore, external cavity lasers (ECLs) become the first choice to replace traditional lasers to supply narrow linewidth of~sub 100 kHz and wide tuning range. The ECLs based on blazed diffraction gratings [4] are of wide tuning range and narrow linewidth, but suffer from huge size, complex package, and difficult alignment, which increase the cost and harm the stability of the lasers. On the other hand, hybrid integration between photonics chips and semiconductor lasers provides an ideal method to fabricated ECLs.…”