Alexander Betin

2-kW Average Power CW Phase-Conjugate Solid-State Laser

We have demonstrated stable operation of a 2-kW Yb:YAG phase-conjugate master oscillator power amplifier (PC-MOPA) laser system with a loop phase-conjugate mirror (LPCM). This is the first demonstration of a continuous wave (CW)-input LPCM MOPA operating at a power greater than 1 kW with a nearly diffraction-limited output beam. The single-pass beam quality incident on the LPCM varied with the specific operating conditions, but it was typically ~20 times diffraction-limited (XDL). The measured beam quality with an MOPA output power of 1.65 kW was 1.3 XDL.

Laser amplifier development for IPDA Lidar measurements of CO2 from space

Accurate global measurements of tropospheric CO2 mixing ratios are needed to better understand the global carbon cycle and the CO2 exchange between land, oceans and atmosphere. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar as a candidate for the NASA’s planned ASCENDS mission to allow global measurements of atmospheric CO2 column densities from space. Our group has developed and demonstrated an airborne IPDA lidar for this purpose. It uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), and atmospheric backscatter profiles in the same path. In the airborne lidar, both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space version of this lidar must have a much larger laser power-telescope area product to compensate for the signal losses in the ~40x longer range. An analysis of signal to noise ratios indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, that 1.5 to 2 mJ laser energy is required to attain the needed measurement precision. To meet the laser energy requirements we have pursued two parallel power-scaling approaches for the space laser. These include a single-amplifier approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA) and a parallel amplifier approach using multiple (typically 8) large mode area (LMA) fiber amplifiers. In this paper we summarize the laser amplifier design approaches and preliminary results.

Highly efficient Yb:YAG Master Oscillator Power Amplifier Laser Transmitter for Future Space Flight Missions

In this paper we will discuss our development effort on a highly efficient master oscillator power amplifier (MOPA) laser transmitter for future space flight missions.

2-kW average power phase-conjugate master oscillator power amplifier

We have demonstrated stable operation of a 2-kW Yb:YAG phase-conjugate master oscillator, power amplifier (PC-MOPA) laser system with a loop phase-conjugate mirror (LPCM). This is the first demonstration of a CW-input LPCM MOPA operating at a power greater than 1 kW with a nearly diffraction-limited output beam. The single-pass beam quality incident on the LPCM varied with the specific operating conditions, but it was typically ~ 20 times diffraction-limited (XDL). The measured beam quality with a MOPA output power of 1.65 kW was 1.3 XDL.

A Master-Oscillator-Power-Amplifier 2-micron Laser Using Fiber Phase-Conjugate Mirror

For the first time, a 2-micron master-oscillator-power-amplifier laser using a fiber based phase conjugation mirror has been demonstrated. The beam quality improvement and 56% of the PCM reflectivity have been achieved.

Phase-Conjugated 2-μm Laser System

For the first time, beam quality improvement of 2 μm laser using fiber based phase conjugation mirror has been demonstrated. Single frequency operation is necessary to lower threshold. The reflectivity of the PCM is ~50%.