Achievements in reporting period:

• List of working documents

Minutes of the AMSTAR+ kick-off meeting (May 2009)
AMSTAR+ Work Plan in 2009

• AMSTAR+ Kickoff Meeting at the IRAM Headquarters near Grenoble (May 20th, 2009)
  

The AMSTAR+ kickoff meeting was held on May 20th, 2009 at the IRAM headquarters near Grenoble, France. It was attended by 20 scientists and engineers from 13 laboratories participating to AMSTAR+ . Peter Wilkinson, Principal Investigator of the RadioNet JRA APRICOT, a JRA which aims like AMSTAR+ at developing focal plane array receivers, although at longer wavelengths, also attended the meeting. The morning session was devoted to a brief report on the RadioNet kickoff and Board meetings and to the presentation of the 4 main tasks of AMSTAR+ and to reports on the advancement of the work on these tasks since January 2009. The afternoon was devoted to a general discussion on the technical challenges that may be common to the different Tasks and groups (advantages of integrated and balanced amplifiers and/or mixers; procurement of HEMT devices; Josephson current suppression; waveguide vs quasi-optical injection of LO) and to a visit of the IRAM laboratories. The different presentations and the Kickoff Meeting minutes will be posted on the AMSTAR+ Wiki site.

• Main Activities during 2009 Q1 and Q2 and Work Plan for Q3 and Q4:

Task 1: Prototype W-band heterodyne array module using metamorphic HEMT technology

The collaboration IAF/IRAM/MPIfR started with the characterization at cryogenic temperatures of 25 GHz low noise amplifiers (LNA) with GaAs devices fabricated with the IAF metamorphic technology. The S parameters of the cooled LNAs were measured up to 50 GHz. The device gate length turned out to be a critical parameter. Oscillations appeared upon cooling 100 nm gate length devices, but fortunately, not with 50 nm devices. It has been decided to switch to 50 nm gate length. New devices with 50 nm gate length are being produced and will be tested. Deliverable in 2009: progress reports on the tests.

Task 2 Integrated pixel and photonic LO for large focal plane array

The goal is to develop sideband-separating (2SB) SIS mixers with a wide IF bandwidth, that are fully integrated from horn to LNA and have a reduced footprint (25mmx25mm per pixel) and length (30 mm), so that they could be incorporated first in a prototype 3 pixel block, then in a 7×7 element array that would fit in the focal plane of the IRAM 30-m telescope. The mixers of one 3-pixel block would be driven by a photonic LO under development at RAL.

During the first semester of 2009 months, a design was made of a compact pixel with a sideband-separating mixer making use of proven technologies. The sideband-separating mixer consists of waveguide couplers, DSB SIS mixers, and an IF coupler. The DSB SIS mixer has been designed for RF frequencies from 200 to 280 GHz with an IF band of 4-12 GHz. It will also serve for the study of direct coupling with the LNA. The work during the second semester will be devoted to the design of the on-chip integrated mixer and of the LNA, as well as that of the photonic LO which will start in July. Deliverables in 2009 will be progress reports.

Task 3: Sub-millimetre Wave Heterodyne Focal Plane Arrays

A mechanical concept of a compact 2SB mixer block suitable for FPA at 650 GHz has been developed at SRON. Detailed drawings are produced to make a test fit set and verify the produce ability. A new junction design involving high current density with an AlN barrier is being developed at TuDelft and SRON taking into account magnetic field dependent losses in tuning structures.

Task 4: Low noise heterodyne mixers for focal plane arrays in the 1-2 THz frequency band.

Goal is extension of heterodyne FPA technology into the Terahertz windows. For this frequency range, the first priority is the development of detecting devices, HEB and SIS. Work has started on Q1,Q2 at SRON and TuD to study the ultimate performance of HEB mixers at super-THz frequencies and to shape THz QCL to have a Gaussian far field beam required for local oscillator. On the Chalmers' side, testing in the clean room Si-etching technology for fabrication of the mixer active component (SIS or HEB) has been going on together with extensive simulations of the thermal behavior of the membrane based SIS and HEB mixers and 3D electromagnetic simulations to find the configuration of the choke structure the most tolerant to vertical miss-alignment in the substrate channel. Finally, early HEB devices built at Chalmers were re-tested to checjk for possible aging and try to determine a lifetime.

• Meetings attended by people involved in AMSTAR+

Int. Symposium on Space Terahertz Technology, Charlottesville, USA, on April 20-22, 2009 (8 presentations by the participants to AMSTAR+)
RadioNet Enginieering Forum on “Low Noise Measurements” at Chalmers, Sweden, on June 23-24, 2009 4 presentations by the participants to AMSTAR+)

Problems / Issues

• Issues - organisational, administrative or other problems foreseen

The break down of the AMSTAR+ WP into Tasks and subtasks headed by different institutes (12 in total) make it difficult to issue a detailed report (and more particularly a financial report) every 3 months. It seems odd that RadioNet requests to its JRAs a planning of their research activities in steps as short as 3 months, when itself it is not able to tell with such an accuracy when the JRAs will get any funds from the EC!

• Red flags - major problems

So far, none, except for the funding by the EC which has not yet arrived.

Forward Look

• Plan for next quarter/half year– 3 and 6 month outlook, more detail in first 3 months (including budget)

Task 1: fabrication and cryogenic test of new devices.
Task 2: design of the on-chip integrated mixer and of the LNA, as well as that of the photonic LO which will start in July.
Task 3: design at SRON and TuDelft a new AlN barrier junction involving high current density that takes into account the losses in the tuning structures.
Task 4: continue work on HEBs and QCLs at SRON and TuDelft. Continue improvement of Si-etching process and of waveguide technology for THz frequencies in Chalmers.

• Expected milestones/deliverables

No milestones during the next 6 months, which will be mainly devoted to design studies. Deliverables will take the form of progress and/or test reports.

• Expenditures - equipment, material and services

Table in preparation

• Person month spent/to be spent until next EC Report

in preparation

• Number of Persons working in JRA