Zhouming Feng

An efficient compact 300 mW narrow-linewidth single frequency fiber laser at 1.5 μm

An efficient single frequency fiber laser by using a newly-developed Er(3+)/Yb(3+) co-doped single mode phosphate glass fiber with the net gain coefficient of 5.2 dB/cm and propagation loss coefficient of 0.04 dB/cm has been demonstrated. Over 300 mW stable continuous -wave single transverse and longitudinal mode seed lasering at 1.5 microm has been achieved from a 2.0 cm-long active fiber. The measured slope efficiency and the calculated quantum efficiency of laser emission are found to be 30.9% and 0.938 +/- 0.081, respectively. It is found that the linewidth of the fiber laser is less than 2 kHz, and the measured relative intensity noise (RIN) is around -120 dB/Hz in the frequency range of 50 to 500 kHz.

Low noise single-frequency single-polarization ytterbium-doped phosphate fiber laser at 1083 nm

We present a low noise single-frequency and single-polarization distributed Bragg reflector fiber laser at 1083 nm by using a 1.8 cm long newly developed ytterbium-doped phosphate single mode glass fiber. The maximum output power is more than 100 mW with a slope efficiency of >29.6%. The signal to noise ratio is higher than 61 dB and the laser linewidth of less than 2 kHz is estimated. The obtained relative intensity noise for frequencies of over 4.0 MHz is less than -150 dB/Hz, which approaches the shot noise limit. The achieved linear polarization extinction ratio is more than 30 dB.

Upconversion emission in multi-doped glasses for full colour display

Upconversion luminescence characteristics of a multi-rare-earth-doped 0.05K2O?0.1ZnO?0.1BaO?0.2PbO?0.2GeO2?0.35TeO2 glass have been investigated under 976?nm excitation for potential use in full colour displays. Two luminescence ions, Er3+ and Tm3+, were used as blue, green and red emitters to control the colour of the emitted light. Sensitizer ions, Yb3+, were used to increase the upconversion emission intensity. With the substitution of Er3+ for Tm3+, the intensities of the blue, green and 657?nm upconversion emissions simultaneously increase.

A 1014 nm linearly polarized low noise narrow-linewidth single-frequency fiber laser

We present the demonstration of a compact linearly polarized low noise narrow-linewidth single-frequency fiber laser at 1014 nm. The compact fiber laser is based on a 5-mm-long homemade Yb(3+)-doped phosphate fiber. Over 164 mW stable continuous-wave single transverse and longitudinal mode lasing at 1014 nm has been achieved. The measured relative intensity noise is less than -135 dB/Hz at frequencies of over 2.5 MHz. The signal-to-noise ratio of the laser is larger than 70 dB, and the linewidth is less than 7 kHz, while the obtained linear polarization extinction ratio is higher than 30 dB.

Microwave Signal Generation From a Dual-Wavelength Single-Frequency Highly

Narrow linewidth microwave signals generated from a heterodyne detection configuration of a dual-wavelength (DW) single-frequency highly Er3+/Yb3+ co-doped phosphate fiber laser is presented. The oscillating cavity of the fiber laser consists of a dual-channel narrow-band fiber-Bragg-grating (DC-NB-FBG), a 0.7-cm-long Er3+/ Yb3+ co-doped phosphate fiber and a wideband FBG (WB-FBG). The wavelength selecting gratings are spatially separated to create partially separated resonant cavities. Highly Er3+/Yb3+ co-doped phosphate fiber ensures that the mode competition is relatively weak under low pump power. DW single-frequency lasing with laser linewidths of 3 kHz is achieved. A 12.014-GHz microwave signal with a 3-dB linewidth of 3 kHz is obtained from the heterodyne detection of the DW fiber laser.

\hbox{Er}^{3+}/\hbox{Yb}^{3+}

A significant broad-bandwidth near-shot-noise-limited intensity noise suppression of a single-frequency fiber laser is demonstrated based on a semiconductor optical amplifier (SOA) with optoelectronic feedback. By exploiting the gain saturation effect of the SOA and the intensity feedback loop, a maximum noise suppression of over 50 dB around the relaxation oscillation frequencies and a suppression bandwidth of up to 50 MHz are obtained. The relative intensity noise of -150  dB/Hz in the frequency range from 0.8 kHz to 50 MHz is achieved, which approaches the shot-noise limit. The obtained optical signal-to-noise ratio is more than 70 dB. This near-shot-noise-limited laser source shows important implications for the advanced fields of high-precision frequency stabilization, quantum key distribution, and gravitational wave detection.

Co-Doped Phosphate Fiber Laser

An all-fiber 10.9 W single-frequency one-stage linearly-polarized master-oscillator power amplifier (MOPA) laser at 1560 nm has been demonstrated. The laser linewidth is less than 3.5 kHz and the polarization-extinction ratio (PER) is greater than 24 dB. The measured signal-to-noise ratio (SNR) is higher than 70 dB and the optical-to-optical conversion efficiency is 29.5%. No obvious stimulated Brillouin scattering and the devastating effects of unwanted coupling light were observed.

Broad-bandwidth near-shot-noise-limited intensity noise suppression of a single-frequency fiber laser

A novel linearly frequency modulated narrow linewidth single-frequency phosphate fiber laser has been demonstrated. The output power of the laser is more than 40 mW. A maximum frequency excursion of more than 700 MHz at the modulating bandwidth of 1 kHz has been achieved. Single longitudinal mode operation under modulation is confirmed and the linewidth of the laser is measured to be less than 2 kHz. This type of laser source shows real promise for applications in coherent optical frequency domain reflectometry.

10.9 W kHz-linewidth one-stage all-fiber linearly-polarized MOPA laser at 1560 nm

A spectrally clean kHz-linewidth single-polarization single-frequency distributed Bragg reflector Yb-doped phosphate fiber (YPF) laser at 1120 nm (> 1100 nm) for the first time is demonstrated. By enhancing the reflectivity of output fiber Bragg grating and optimizing the length of YPF to implement the effective ASE suppression and single-longitudinal-mode long-wavelength lasing, a stable output power of over 62 mW is achieved from a 31-mm-long highly YPF with a linewidth of 5.7 kHz. The signal to noise ratio of > 67 dB, the polarization extinction ratio of > 25 dB, and the relative intensity noise of < -150 dB/Hz for the frequencies above 10.0 MHz are obtained in such single-frequency fiber laser. This narrow linewidth fiber laser is an ideal laser source to generate the coherent single-frequency 560 nm light via frequency doubling for biochemical analysis application.

A linearly frequency modulated narrow linewidth single-frequency fiber laser

An ultra-narrow linewidth full C-band tunable single-frequency linear-polarization fiber laser based on self-injection locking has been demonstrated. By the use of a tunable narrow-band fiber Fabry-Perot interferometer, the laser wavelength could be flexibly tuned from 1527 to 1563 nm with linewidths of < 700 Hz. The laser frequency noise is less than 40 dB re Hz/Hz1/2 at low frequencies (< 100 Hz) and reaches -5 dB re Hz/Hz1/2 at around 25 kHz. The measured relative intensity noise (RIN) is less than -130 dB/Hz with regard to frequencies of over 3 MHz, while the obtained linear polarization extinction ratio (LPER) is higher than 28 dB. This ultra-narrow linewidth low-noise tunable single-frequency linear-polarization fiber laser provides a promising candidate for high-order quadrature amplitude modulation (QAM) optical communication system.