Measurement of the wavefront of a laser diode system for intersatellite communication by a Jamin double-shearing interferometer

The frame of a laser diode transmitter for intersatellite communication is concisely introduced. A simple, novel and visual method for measuring the diffraction-limited wavefront of the transmitter by a Jamin double-shearing interferometer is proposed. To verify the validity of the measurement, the far-field divergence of beam is additionally rigorously analysed in terms of the Fraunhofer diffraction. The measurement, the necessary analyses and discussion are given in detail. By directly measuring the fringe widths and quantitatively interpreting the interference fringes, the minimum detectable wavefront height (DWH) of the wavefront is only 0.2 gimel (the distance between the perfect plane wavefront and the actual wavefront at the transmitting aperture) and the corresponding divergence is only 65.84 mu rad. This indicates that the wavefront approaches the diffraction-limited condition. The results show that this interferometer is a powerful tool for testing the semiconductor laser beam's wavefront, especially the diffraction-limited wavefront.

Laser diode array side-pumped acousto-optic induced unidirectional operation Q-switched Nd : YAG slab ring laser

A laser-diode array (LDA) side-pumped Nd:YAG slab ring laser is described that incorporates a prism-shaped acousto-optic modulator to enforce unidirectional operation and Q-switching. When pumped by the maximum power of 50 W, Q-switched energies of 3.6 mJ and 50 ns duration, corresponding to a peak power of 72 kW, are obtained. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01306-9].

5.5W CWYb3+ : Y2O3 ceramic laser pumped with 970 nm laser diode

CW laser output has been demonstrated for polycrystalline transparent 10 at.% Yb3+-doped Y2O3 ceramics. End-pumped with 970 nm laser diode, a maximum output power of 5.5 W has been obtained with absorbed pump power of 31.1 W. The slope efficiency is 25% while the threshold pump power is 5.6 W. Saturation is not observed in our experiments, indicating higher laser output can be expected with higher pump power. (C) 2004 Elsevier B.V. All rights reserved.

Line-width reduction of a laser diode array using an external cavity with two feedback mirrors

A novel Littman-Metcalf external cavity laser diode array with two feedback mirrors is introduced. The line-width broadening effect caused by smile can be reduced by the novel external cavity. At the drive current of 16A, the line-width is narrowed to 0.1nm from free-running width of 1.6nm with output efficiency of 84%.

Beam quality improvement of laser diode array by using off-axis external cavity

A novel off-axis external cavity is designed for laser diode array to improve the beam quality. In this external cavity, a circle aperture with variable size is used as a spatial filter. The diameter of aperture is optimized to 1.2mm and the off-axis angle of external cavity is optimized at 2.6 deg. In the optimal case, the beam parameter product (BPP) of laser diode array is reduced to 121 mm. mrad from 1050 mm. mrad with external cavity optical efficiency of 81%. (C) 2007 Optical Society of America.

Beam collimation of high-power laser diode array with graded-index fiber lens array

Graded-index (GRIN) fiber lens arrays are fabricated from commercial GRIN fibers to collimate a high-power laser diode array. The beam divergence angles are reduced to 4.2 and 14.7 mrad in the fast and slow axes, respectively. The influences of smile and fluctuation in fiber length are discussed. Using an aspherical focal lens system, about 74% power can be launched into a fiber with a numerical aperture (NA) of 0.22 and a core diameter of 400 mu m. (c) 2008 Society of Photo-Optical Instrumentation Engineers.

Laser-diode-pumped Cr4+,Nd3+: YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr,Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate Varies with pump power. (C) 2000 Optical Society of America OCIS codes: 140.0140, 140.2020, 140.3380, 140.3480, 140.3540, 140.3580.

Very high modulation efficiency two-sections tapered laser diode at 1060nm for free space optical communications

High-power (more than 500 mW) and high-speed (more than 1 Gbps) tapered lasers at 1060 nm are required in free-space optical communications and (at lower frequencies of around 100 MHz) display applications for frequency doubling to the green. On a 3 mm long tapered laser, we have obtained an open eye diagram at 1 Gbps, together with a high extinction ratio of 11 dB, an optical modulation amplitude of 530 mW, and a high modulation efficiency of 13 W/A. On a 4 mm-long tapered laser, we have obtained an open eye diagram at 700 Mbps, together with a high extinction ratio of 19 dB, a high optical modulation amplitude of 1.6 W, and a very high modulation efficiency of 19 W/A. On a 6 mm-long tapered laser, we have obtained a very high power of 5W CW and a very high static modulation efficiency of 59.8 W/A. © 2011 SPIE.