Shibin Jiang

Low-noise narrow-linewidth fiber laser at 1550 nm (June 2003)

We present a compact integrated fiber laser with more than 200 mW of output power. It combines polarized fiber output with very narrow linewidth of less than 2 kHz. The coherence length of the laser is measured to be longer than 5 km. The laser features high mode stability of less than /spl plusmn/10 MHz over hours. The relative intensity noise (RIN) spectrum is dominated by a peak at the relaxation oscillation frequency and is shot-noise limited otherwise. The RIN peak at 1 MHz is reduced to /spl sim/-130 dB/Hz by integrating a negative feedback circuit. In addition to thermal wavelength tuning, the laser frequency can be modulated at a bandwidth of up to 10 kHz via the piezoelectric effect.

Optical transitions and visible upconversion in Er3+ doped niobic tellurite glass

Er3+ doped Nb2O5–TeO2 (NT) glass suitable for developing optical fiber laser and amplifier has been fabricated and characterized. Intense and broad 1.53 μm infrared fluorescence and visible upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. For 1.53 μm emission band, the full width at half-maximum is 51 nm, the fluorescence lifetime is 2.6 ms, and the quantum efficiency is ∼100%. The maximum emission cross section is 8.52×10−21 cm2 at 1.532 μm, and is higher than the values in silicon and phosphate glasses. Under 798 nm excitation, efficient 531, 553, and 670 nm upconversion emissions are due to two-photon absorption processes. The “standardized” efficiency for the green upconversion light is 9.5×10−4, and this value is comparable to that reported for Er3+/Yb3+ codoped fluoride glasses. Intense visible upconversion fluorescence in Er3+ doped NT glass can be used in color display, undersea communication, and infrared sensor.

Er3+-doped phosphate glasses for fiber amplifiers with high gain per unit length

The effect of the types of alkaline earth metal ions (Mg 2+ , Ca 2+ and Ba 2+ ) and concentration of Al 2 O 3 and BaO on the refractive index and the effective emission linewidths of the 4 I 13/2 - 4 I 15/2 transition of Er 3+ ions in phosphate glasses, 64P 2 O 5 . 12Al 2 O 3 . 3.5(Er 2 O 3 + La 2 O 3 ) . 20.5MO (M = Mg, Ca, Ba) and 64P 2 O 5 . 3.5(Er 2 O 3 + La 2 O 3 ) . (21.5-x)Al 2 O 3 . (11 +x)BaO (x =0, 3.5, 6.5 and 9.5), were investigated. A single mode Er 3 doped phosphate glass fiber with a core diameter of 4 μm was fabricated by the rod-in-tube technique. A new Er 3+ doped fiber amplifier is demonstrated pumping with a 980 nm fiber pigtailed-laser diode. A gain per unit length greater than 2 dB/cm is demonstrated, which is the largest gain per unit length for fiber amplifiers to our knowledge.

Highly efficient high-power thulium-doped germanate glass fiber laser

A 64 W fiber laser at 1.9 microm with a slope efficiency of 68% with respect to the launching pump power at 800 nm was demonstrated in a one-end pump configuration using a piece of 20 cm long newly developed thulium-doped germanate glass double-cladding single-mode fiber. A quantum efficiency of 1.8 was achieved. An output laser power of 104 W at 1.9 microm was demonstrated from a piece of 40 cm long fiber with a dual-end pump configuration.

Mode-locked 2 μm laser with highly thulium-doped silicate fiber

We report self-starting passively mode-locked fiber lasers with a saturable absorber mirror using a piece of 30-cm-long newly developed highly thulium (Tm)-doped silicate glass fibers. The mode-locked pulses operate at 1980 nm with duration of 1.5 ps and energy of 0.76 nJ. This newly developed Tm-doped silicate fiber exhibits a slope efficiency of 68.3%, an amplified spontaneous emission spectrum bandwidth (FWHM) of 92 nm, and a gain per unit length of greater than 2 dB/cm. To the best of our knowledge, it is the first demonstration of mode-locked 2 mum fiber laser using shorter than 1-m-long active fiber, which paves the way for the demonstration of mode-locked fiber laser at 2 mum with gigahertz fundamental repetition rate.

Highly stable low-noise Brillouin fiber laser with ultranarrow spectral linewidth

We demonstrate an all-fiber high-power single-frequency Brillouin fiber ring laser with maximum power of 100 mW at 1.55 mum, which is actively stabilized by using the Pound-Drever-Hall frequency-locking scheme. Significant reduction (~20dB) of both relative intensity noise and frequency noise was observed in the Brillouin Stokes radiation as compared with those noises of its pump source, a narrow-linewidth Er-doped fiber laser. Ultranarrow spectral linewidth of the Brillouin fiber lasers was investigated by both delayed self-heterodyne technique and heterodyne beat technique between two independent Brillouin fiber lasers

Spectral properties of erbium-doped lead halotellurite glasses for 1.5 μm broadband amplification

Abstract The spectral properties of the Er 3+ -doped lead halotellurite glasses, PbX 2 –TeO 2 (X=F, Cl, Br), were measured and analyzed with Judd-Ofelt and McCumber theories. These glasses showed high refractive indices, high cross-sections for both absorption and stimulated emission, and very broad bandwidths for the 1.5 μm band. The bandwidths of the 1.5 μm band, which have substantial magnetic dipole transition component, increased significantly with the refractive index of the host materials. The halotellurite glasses have very good glass formation ability or glass stability. The halotellurite glasses will be the promising host materials for 1.5 μm broadband amplification.

Narrow linewidth fiber laser for 100-km optical frequency domain reflectometry

A diode-pumped single-frequency piezoelectrically tuned fiber laser with narrow spectral linewidth has been used as a light source in applications for long-range coherent frequency-domain reflectometry. Frequency-modulated continuous-wave (FMCW) measurements of Rayleigh back-scattering and Fresnel reflection from a 95-km-long fiber have been demonstrated without the use of an optical amplifier. This is, to our knowledge, the longest distance measurement with FMCW. The high sensitivity and dynamic range of the long-range backscattering measurements benefit from the extremely long coherence length of the narrow linewidth fiber laser, which has been estimated to be 210 km in air.

Single-frequency narrow-linewidth Tm-doped fiber laser using silicate glass fiber

Single-frequency laser operation near 2 microm has been demonstrated in an all-fiber short-cavity (2-6 cm) distributed feedback laser cavity using both cladding- and core-pump configurations in a newly developed heavily Tm-doped multicomponent silicate glass fiber. Using a single-mode Er-doped fiber laser at 1575 nm as a core-pump source, a 2-cm-long distributed Bragg reflector fiber laser delivers single-frequency output at 1950 nm with laser linewidth less than 3 kHz, which is, to the best of our knowledge, the narrowest linewidth demonstrated to date from any 2 microm single-frequency laser.

Er3+ doped Na2O–Nb2O5–TeO2 glasses for optical waveguide laser and amplifier

Er3+ doped Na2O–Nb2O5–TeO2 (NNT) glasses suitable for making optical waveguide devices has been fabricated and characterized. Intense 1.53 μm infrared fluorescence and green upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. The optical absorption, the Judd–Ofelt parameters and the spontaneous transition probabilities have been measured and calculated. The quantum efficiency of 1.53 μm emission band is proved to be ~100%. The maximum emission cross-section is 1.02×10−20 cm2 at 1.533 μm, and it is more than 30% higher than the values in silicate and phosphate glasses. Under 798 nm excitation, strong green and weak red upconversion luminescence was observed at room temperature. The 546 nm green band shows a broad full-width at half-maximum of 16 nm. Intense and broad green upconversion fluorescence in Er3+ doped NNT glass can be used in colour display, undersea communication and infrared sensor. High concentration of Na2O is a benefit to developing waveguide device from the glass.